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Tech Questions


Here you'll find some technical questions that you may expect to be asked in an airline interview. Use this as a study guide, but of course you should verify the accuracy of all the answers given below from another source, as the information may be out of date or even in error. The list is by no means exhaustive, but it should give you a general idea of the technical knowledge you need to have.


Questions


1. What is pressure altitude?

Pressure altitude is the height above the standard datum plane of 1013Hpa when above 10,000 ft in Australia


2. What do you know about the RR Trent engine?

The Trent is a three-shaft and second-generation hollow titanium wide-chord

fan high bypass ratio engine. Fan diameter: Trent 800 at 110 inches (2.79 meters).

Eight-stage IP compressor; six-stage HP compressor; single annular combustor with

24 fuel injectors (Trent 700 and 800); single-stage HP turbine; single-stage IP turbine; five-stage LP turbine (Trent 800, 500, 900 and 600).

http://www.rolls-royce.com/civil/products/turbofans/default.htm


3. How does an INS work?

3 Platform with rotating mechanical gyros updated by DME / DME, VOR / DME, VOR / VOR. System is self-contained. Timing accuracy remains a critical shortfall. Integrity could either be acceptable, in the case of a complete INS failure, or unacceptable, in the case of insidious drift rates.

http://www.navcen.uscg.gov/pubs/gps/crd/crdfp-3.html

http://www.gfy.ku.dk/~cct/WP333/WP333.htm


4. How does an Omega work?

Very low frequency (10KHz – 14 KHz) Phase synchronizing system. Initially used for submarine navigation. Last antenna switch off end ’97. Antenna in USA, Norway, France, Japan, Australia.

http://www.navcen.uscg.gov/omega/ogeninfo/omegaff.htm


5. How do winglets work?

Improve performance / reduces drag by reducing wingtip vortices between high pressure and low pressure zone at the end of the wing. The main advantage is a less fuel flow.

http://www.visionengineer.com/aero/winglet.shtml


6. What are the advantages of the B747-400?

Range, higher Payload, no ETOPS limitation.

It also presents major aerodynamic improvements over earlier 747 models, including the addition of winglets to reduce drag, a new flight deck with new avionics and the latest in-flight entertainment systems.

Boeing claims that it has also the lowest operating cost per ton-mile in the industry.

http://www.boeing.com/commercial/747family/background.html


7. What type of engine is on your aircraft? What is the RPM?

RR Trent 884 / 892  RPM on the N1 is?

http://www.rolls-royce.com/civil/products/turbofans/default.htm


8. Explain Dutch roll

The 'Dutch Roll' is a combination of rolling and yawing, which results in an elliptic motion of the wingtips. Ailerons bank / Rudder opposite to maintain HDG / or a point on horizon.

http://www.whittsflying.com/Page4.71Landing%20in%20Winds.htm#anchor94041


9. How does an iso-contour radar work?

Contour or iso-counter refers to a weather radar display presentation that blanks the echo returns in the center of a storm cell. The area blanked out is called contour and corresponds to the return levels that exceed a predetermined threshold.

http://www.flwsradar.com/Tech_Lit/Glossary/GLOSSARY.PDF


10. Is there a critical engine on a propeller / jet aircraft?

For an engine with clockwise rotating props, this produces left roll. The critical engine would be the outboard, left engine. There is no critical engine on an jet aircraft as the corresponding systems are redundant.

http://142.26.194.131/aerodynamics1/Multi/Page3.html


11. What is the difference between MRC and LRC?

LRC is 1% less then MRC but with a significant increase of speed.


12. Define endurance/ range on the drag curve

http://www.allstar.fiu.edu/aero/lift_drag.htm

http://www.aoe.vt.edu/~lutze/AOE3104/range&endurance.pdf


13. How do flaps affect the take-off ground run?

Less flaps longer takeoff run but better climb vv.


14. What is a microburst? What do you do about it?

Two extreme types of microburst. One is the extremely dry environment in which moist convection is just barely possible, and the other is the extremely wet environment, which can produce microburst embedded in very heavy rain. Avoid them!

http://www.cimms.ou.edu/~doswell/microbursts/Figure_08.JPG


15. What is the biggest hazard in heavy rain on final approach?

Reduced visibility, wind shear, reduced landing performance ( aquaplaning, skid )


16. What is VMCA on the B777?

VMCA on TO2 884 = 93 kts, VMCA on TO2 892 = 97 kts, VMCA on TO2 892ER = 87 kts


17. What is the relationship between VMCG and V1?

VMCG≤ V1


18. What is the difference between a B 747 classic and the B747-400?

Payload, Range, Efficiency, cockpit layout including avionics, aerodynamics,

http://www.airliners.net/info/stats.main?id=97

http://www.boeing.com/commercial/747family/technical.html


19. What is the difference between the B777 wing and the B747 wing?

Wing area of 747-400 is larger. 777’s has no winglets and is more advanced in design.


20. What are Kueger flaps?

Nose flaps formed by rotating part of lower wing surface. Advantage increased chord, disadvantage higher drag, higher production cost

http://www.hq.nasa.gov/office/pao/History/SP-468/ch10-5.htm


21. When do you turn on engine anti-ice?

Whenever icing conditions are anticipated or visible moisture, visibility less then 1 NM, temperature less then 10˚C down to -40˚C

22. What is Direct Lift Control (DLC)?

Spoiler movement to increase ROD without changing Thrust / Pitch


23. What are the advantages of a fan engine?

Higher Thrust due to high Bypass ratio, less fuel flow, high efficiency, less noise

24. Give six reasons for spoilers?

High speed turn device, Drag on ground, Speed brakes, DLC, destroy lift after touch down, Redundancy due 3 HYD systems?


25. What are active controls?

Active controls enable an airplane to pull air across the plane in specific directions rather than passively letting the air flow over it. Basically ailerons, rudder and elevator, for roll, yaw and pitch control.  


26. What is the purpose of a Mach trimmer?

In a flight control system, an automatic control sub-system which provides pitch trim of an aircraft as a function of mach number. The mach trim system provides automatic elevator displacement as a function of mach number in the mach tuck (nose down) region. Mach data from the air data computer is used to generate a servo position command signal. This signal is applied to the mach trim actuator. The actuator provides elevator pitch-up position to maintain the correct attitude when airplane mach tuck speed is attained. The mach trim actuator changes the position of the column neutral point without altering feel/force characteristics.

http://digilander.libero.it/andreatheone/dfcs.htm


27. Why are bleed valves fitted to jet engines?

To regulate the internal pressure during all parts of flight, prevent stalling an engine.

They also serve for the purpose of air extraction for air conditioning and pressurization.


28. Define the two major types of drag?

  • Parasite drag is defined as all drag that is not associated with the production of lift
  • Induced drag is that portion of total drag associated with the production of lift

http://www.navygouge.com/api/basics/ELOs/aero.html


29. What are the forces acting upon an aircraft in flight?

Thrust-Drag / Lift-Weight

http://www.lerc.nasa.gov/WWW/K-12/airplane/smotion.html


30. What are the advantages and disadvantages of the INS system?

System is self-contained. Timing accuracy remains a critical shortfall. Rotating gyros causing drag and that causes inaccuracy over the time period.

http://www.navcen.uscg.gov/pubs/gps/crd/crdfp-3.html


31. What are the purposes roll and yaw dampers?

The prime function of a yaw damper is to minimize Dutch Roll by providing automatic rudder displacement proportional to and opposing the amount of yaw experienced.

http://www.boeing-727.com/Data/systems/infoyawdampers.html


32. What is a super-stall?

Turbulent air due high pitch reaches the aft section of the aircraft and causes a super stall.

http://www.aviationshop.com.au/avfacts/editorial/tipstall/default.asp


33. What are the four reasons for a variable incidence tail plane?

Over rotation, wrong takeoff speeds, tailwind, cargo shift during rotation,


34. What are the three types of hydroplaning?

Dynamic Hydroplaning ( Standing water ), Viscous Hydroplaning ( dust, dirt, rubber ) Rubber reversion hydroplaning ( high-pressure steam due to hot brakes melting ice )

http://www.jet-jobs.com/articles/hydropln.html#dy

http://www.jet-jobs.com/articles/hydropln.html#vis

http://www.jet-jobs.com/articles/hydropln.html#rub


35. What is the relationship of V1, VR and V2?

VMCG ≤ V1 ≤ VMBE ≤ 1.05 VMCG ≤ VR ≤ 1.1 VMCA ≤ V2


36. What is ISA (ICAO standard atmosphere)?

Sea Level Barometric Pressure of 29.92 inches of Mercury (in. Hg), 1013,25 Hpa

Sea Level Temperature of 15° Celsius

Relative humidity of 0 %

Standard temperature lapse rate of 2° C per 1000 feet altitude

Standard pressure lapse rate of 1 in. Hg per 1000 feet altitude

A standard decrease in density as altitude increases

http://www.uncletom2000.com/gs/perf.htm


37. What is EPR (engine pressure ratio)?

EPR = PT8/PT2   PT8 = Outlet pressure / PT2 = Ram Air Fan pressure

http://www.lerc.nasa.gov/WWW/K-12/airplane/epr.html


38. What are the various ICAO approach limits? (CAT I, CAT II …)

CAT I = 200’-800mCAT II = 100’-350mCAT IIIa = 50’-200mCAT IIIb = 20’-100m

39. What is a CAT (Clear Air Turbulence)?

Erratic air currents that occur in cloudless air between altitudes of 23,000 and 39,000 feet. This turbulence can be caused by small-scale wind velocity gradients around the jet stream, where rapidly moving air is close to much slower air. It is most severe over mountainous areas.

http://www.casa.gov.au/airsafe/trip/turbulen.htm


40. What is wind shear / micro burst?

Wind shear are any rapid change in wind direction or velocity. Severe wind shear is a rapid change in wind direction or velocity causing airspeed changes greater than 15 knots or vertical speed changes greater than 500 feet per minute in the vertical direction. Two extreme types of microburst. One is the extremely dry environment in which moist convection is just barely possible, and the other is the extremely wet environment, which can produce microburst embedded in very heavy rain.

http://www.math.unl.edu/~jfisher/NSF_96/windshear.html

http://www.cimms.ou.edu/~doswell/microbursts/Figure_08.JPG


41. How does an INS find True North?

By entering the present position in LAT / LONG into the INS. The aircraft can’t be moved during the alignment. During the alignment the platforms stabilize and internal compass then finds during the alignment true north.


42. What is the transport wander of an uncorrected gyro?

The systems typically assume the gravity field to be the normal (ellipsoidal) field, i.e. deflections of the vertical are ignored. This gives rise to errors, which for military systems is known to be the primary error source in navigation accuracy.

http://www.gfy.ku.dk/~cct/WP333/WP333.htm


43. What is the rejected takeoff drill?

Call stop, close thrust lever / same time use brakes, raise speed brakes, use thrust reverse, after a complete stop set the barking brake,


44. How is range increased when flying into a headwind?

By selecting LRC or for max. range use MRC


45. Tire temperatures prior takeoff depend upon?

A/C weight, taxi speed, tire pressure, OAT, Airport elevation,


46. What is / are the purposes of vortex generators?

They work by creating a controlled swirl of air, or vortex which actually reduces wind resistance (or aerodynamic drag).

They control boundary layer because they prevent separation by bringing air of high momentum into the boundary layer mainly at high angles of attack thus delaying a stall. They can also be used to control shock-induced separation.

http://www.airtab.com/what.htm

http://www.airtab.com/how.htm


47. How does stall speed vary with C of G?

Highest stall speed is at the most forward CG.

http://www.ntps.com/thapdfs/07stalls.pdf


48. How does VMCA vary with C of G?

Any position forward of full aft effectively lengthens the control arm or distance between the rudder and the point which the aircraft yaws about, subsequently increasing the rudder’s control effectiveness. Better effectiveness means you can fly to a slower speed and still maintain directional control.

http://www.copanational.org/non-members/safety/safetyPPDec00.htm


49. What changes the AOA at the stall?

Lowest sustainable speed for required lift occurs at maximum AOA i.e. stall speed.

http://www.geocities.com/pegasusair_tr/aoa.htm


50. What are the inputs to GPWS?

The GPWS uses inputs from systems providing radio altitude, airspeed/Mach number, landing gear and flap position, and DH setting.

http://www.sasflightops.com/safety/gpws.htm


51. Why are B777 takeoff limits (200, 200 ER) different from (300)?

B777-300 is a stretched version of the B777-200.

B777-200/200ER are same aircraft but with different engines (884/892). Takeoff weight is different because of different destination profiles. (Insurance costs)


52. Initially, on wet runway, what is the most efficient means of breaking?

Reverse thrust and speed brake drag are the most effective during the high speed portion of the landing. At lower speeds brakes are getting more efficient.


53. Landing on a tandem bogie, which brake gets the hottest?

The aft one, because of warmed up air from the forward brakes.


54. What are the purpose of engine relight boundaries?

The same as In-flight Engine Start Envelope


55. Wow does the temperatures affect the speed of sound?

The speed of sound is only dependent on temperature. The speed of sound is faster at higher temperatures because molecules collide more often.

http://hypertextbook.com/facts/2000/CheukWong.shtml


56. What are the wind / gust correction factors for VREF speed?

½ headwind + full gusts up to a maximum of 20 kts.


57. What is a high-lift devices?

Slats and Flaps are High-lift device’s.

http://www.aerodyn.org/HighLift/multi.html


58. What is a high-drag devices?

Spoiler, full flaps,

http://www.1903to2003.gov/essay/Theories_of_Flight/Devices/TH17.htm


59. Why is ERP set by 60 / 80 kts?

Because of increasing Ram effect during takeoff run and therefore more accurate values.


60. What happens to EPR on the takeoff roll?

EPR increases due to ram effect on the engine.


61. What are the effects of compressibility?

Aerodynamic forces depend in a complex way on the compressibility of the air. As an object moves through the air, the air molecules move around the object. If the object passes at a low speed the density of the fluid will remain constant. But for high speeds, some of the energy of the object goes into compressing the fluid and changing the density, which will alter the amount of resulting force on the object. This effect becomes more important as speed increases. Near and beyond the speed of sound shock waves are produced that affect both the lift and drag of an object.

http://www.lerc.nasa.gov/WWW/K-12/airplane/airsim.html


62. What is Mack tuck?

At high speeds (even as low as Mach .85) the nose starts to droop. The initial droop is caused by the center of pressure moving aft on the wing as a result of the air stream over the top of the wing being accelerated to supersonic speeds, even though the overall speed of the aircraft is still sub sonic. By pulling the stick back to correct the flight path the upward deflection of the elevator has been known to cause a shock wave stall at the elevator hinge line. As the speed increases, the aircraft goes into an ever-increasing downward pitch. The nose of the aircraft always tends to pitch nose down as the aircraft transitions from subsonic to supersonic speed. This tendency is called the "Mach Tuck."

http://www.ultralightfloats.com/machtuck_article.htm


63. What happens to stall speed at very high altitudes?

Stall speed increases with higher altitudes because of lesser air density.


64. What do CSD’s (constant speed drives) do?

The CSD or IDG is fitted to the aircraft engine and takes a varying input speed from the engine, mechanically compensating for this varying speed to give a constant output speed to the Generator. An IDG integrates the Generator into the same unit as the CSD, giving a single, more compact unit.

http://www.tarel.com/constant_speed_drives.htm


65. What is mass balance for?

To trim an aircraft within the certified limits.


66. Where does a swept wing stall first?

Swept wing will stall first at the tip.

http://142.26.194.131/aerodynamics1/Drag/Stall_Pattern.html


67. How do you do fuel planning on B777?

Burn off + 5% Contingency + Alternate Fuel + 30 min. Holding Fuel + 700 Kg Taxi


68. How did you prepare technically for the interview?

By being a genius


69. Who was your first instructor?

Mr. XYZ


70. Why is 1 engine the critical engine on a multi-engine prop airplane?

Critical engine is the engine whose failure would most adversely affect the performance or handling qualities of the airplane. Usually, in almost all American twins, the critical engine is the left engine on twins with props that rotate in the same direction. Twins, just like single engine airplanes, have left turning tendencies. These include torque and P-factor. Because the downward bite of the prop has a larger arm from the center of thrust on the right engine than it does on the left in conventional twins, when you lose the left engine the larger arm on the right engine causes more turning tendencies than when you lose the left engine the larger arm on the right engine causes more tuning tendencies than when you lose the right. Put this on top of the left-turning tendencies already existing on the airplane, and you have a severe rolling and yawing reaction of the airplane. On airplanes with counter-rotating props, the downward bite of the descending prop blades are the same on both engines. Thrust line is the distance from centerline of fuselage to downward bite of the propeller. Therefore, no matter which engine you lose it is not the critical engine. You could also consider both engines to be critical since the loss of either on would adversely affect the performance or handling qualities of the airplane.

http://www.glenndale.net/Flight_Training_Stuff/engine_out.htm


71. What advantages does a jet gain from a swept wing?

Swept wing increases the critical much number and decreases the wave drag

http://backoff.pr.erau.edu/gallyt/ae301/Chapter5-Part3.pdf


72. Why do you do de-rated thrust takeoffs in a jet aircraft?

To save engine life


73. How do prevent span-wise flow on a wing?

By installing vortex generators and fences. In this manner a strong boundary layer buildup over the ailerons is prevented.

http://www.centennialofflight.gov/essay/Theories_of_Flight/Transonic_Wings/TH20.htm


74. What are the advantages of MLS or GPS?

MLS allow pilots to pick a path best suited to their type of aircraft and to descend and land from more directions than the ILS. Having different landing patterns can help reduce noise around airports and keep small aircraft away from the dangerous vortices behind large aircraft.

GPS permits land, sea, and airborne users to determine their three dimensional position, velocity, and time, 24 hours a day in all weather, anywhere in the world.

http://www.centennialofflight.gov/essay/Government_Role/landing_nav/POL14.htm

http://www.navcen.uscg.gov/gps/default.htm


75. How many feet in millibar?

About 30 feet


76. What happens to your Mach if you climb at a constant equivalent airspeed / EAS?

Mach gets lower due to decreasing temperature


77. What do you know about CAT III approaches?

CAT IIIa = 50’-200mCAT IIIb = 20’-100mCAT IIIc = no limits

Auto coupled approach with A/T is mandatory for CAT III + Auto brakes for CAT IIIb.

B777 requires following:

EICAS MSG not displayed SGL SOURCE DISPLAYS, SGL SOURCE RAD ALT, SINGLE SOURCE ILS and both ASA and FWD No.1 window heat system operational.

Crew must be certified. Ground equipment meet required approach category.


78. What is the correct technique from Dutch roll?

To use the rudder.

http://web.mit.edu/16.61/www/lectures/lecture18.pdf


79. What are the advantages of MLS and of GPS?

MLS allow pilots to pick a path best suited to their type of aircraft and to descend and land from more directions than the ILS. Having different landing patterns can help reduce noise around airports and keep small aircraft away from the dangerous vortices behind large aircraft.

GPS permits land, sea, and airborne users to determine their three dimensional position, velocity, and time, 24 hours a day in all weather, anywhere in the world.

http://www.centennialofflight.gov/essay/Government_Role/landing_nav/POL14.htm

http://www.navcen.uscg.gov/gps/default.htm


80. What is higher, VMCG or VMCA on a B747-400? Why?

VMCA is always higher than VMCG. VMCA is an air speed while VMCG is a ground  speed.

VMCG≤ V11.05 VMCA≤VR1.1 VMCA≤V2

81. How do you teach a student about VMCA?

VMCA, or minimum control speed air, single engine, is the minimum speed at which a pilot can expect to recover directional control of the airplane within 20 degrees of heading change and then maintain straight flight with not more than five degrees of bank when one engine fails.

http://www.copanational.org/non-members/safety/safetyPPDec00.htm


82. Why do you teach VMCA in the airplane vice the simulator?

Shouldn’t we better teach VMCA in the simulator instead?


83. What does the cost index mean to B777? What things are considered by the FMC system when setting cruise speed in ECON mode?

Cost Index sets variable climb, cruise and descent speeds in the FMC.

ECON considers the cost index set, aircraft weight, altitude and wind factor.


84. How much fuel is used on B 777? How is it distributed?

Left 29100 Kg | Center 79300 Kg | Right 29100 Kg Center Fuel down to about 1000 Kg, then Wing Fuel, at about 13000 Kg. Wing Fuel the scavenge system transfer the remaining Center Fuel the Wing tanks.


85. Your F/O is flying a non-precision approach and has rain on his windscreen. What should you be caution of? What things would you look for if winds hear was expected? What is your recovery technique? What selection will give you TOGA when you hit the go-levers?

Late visual contact to the Rwy, approach lights. Problems during transition from instruments to visual cues.

To be prepared for a go-around. Call out "wind shear recovery" attitude 15˚ nose up, no configuration change until out of wind shear, RA callouts, normal SOP’s.

THR | TOGA | TOGA on the FMC.


86. Tell me about ETOPS. What is an adequate / suitable aerodrome? What things are considered for an airline to be certified for 180 minutes ETOPS?

Adequate airport physically there equipped with a sufficient Rwy, ATC, meteorological and aeronautical service, at least one letdown instrument approach.

Suitable airport is like an adequate airport but with at least 2 separate approach procedures based on 2 aids serving 2 separate Rwy’s + specified WX criteria (VIS, X-wind / gust)

To gain approval for 180 minutes ETOPS, the air carrier must operate the extended range fleet for at least one year in ER-OPS, with an IFSD of approximately .02/1000 hours. The latest landmark in ETOPS was achieved by the Boeing 777, which was authorized for 180 minute ETOPS upon certification.

http://www.ps1fplan.com/mb/docs/etops.html


87. What is the B777 VMO / MMO? Why?

777-200 330 KIAS / .87 Mach

777-300 330 KIAS / .89 Mach

Due to swept wing not to succeed Vmcrit. (Mach tuck)

http://aviation.eng.ohio-state.edu/courses/online/FAA%20Programs/2002_FAA_Key_to_FAA_Publications/TCDS/tcdsvol3/t00001se.pdf


88. Describe, how you would design a high speed aircraft wing?

Delta wings are appropriate plan forms to fly at supersonic and hypersonic speeds.

http://aerodyn.org/Wings/waverider.html


89. Describe a fan engine

The incoming air is captured by the engine inlet. Some of the incoming air passes through the fan and continues on into the core compressor and then the burner, where it is mixed with fuel and combustion occurs. The hot exhaust passes through the core and fan turbines and then out the nozzle, as in a basic turbojet. The rest of the incoming air passes through the fan and bypasses, or goes around the engine, just like the air through a propeller. The air that goes through the fan has a velocity that is slightly increased from free stream. So a turbofan gets some of its thrust from the core and some of its thrust from the fan. The ratio of the air that goes around the engine to the air that goes through the core is called the bypass ratio. Bypass ratio is about 80% of total thrust.

http://www.lerc.nasa.gov/WWW/K-12/airplane/aturbf.html


90. How do spoilers / ailerons work?

Spoilers are used for high and low speed roll control as well as speed brakes in flight and lift destroyer upon landing in order to pressure the gear on landing with the full aircraft weight.

Ailerons are used for low speed roll control as well as lift devices on takeoff with

flaps 5, 15 and 20.


91. You are in a four engine aircraft departing Honolulu for Vancouver. You lose an engine after takeoff. Would you return to a IFR minimum approach in Honolulu or would you continue to Vancouver, where it is CAVOK?

If the engine failure is caused by just an engine problem and not a common problem like volcanic ash, fuel contamination, etc. YES I would continue to my destination if the engineer service would be the same.


92. Tell me about GPS

GPS is defined as the constellation of satellites. GPS permits land, sea, and airborne users to determine their three dimensional position, velocity, and time, 24 hours a day in all weather, anywhere in the world.

http://www.navcen.uscg.gov/gps/default.htm


93. What features make the B777 unique from other aircraft?

The triple bogie landing steer able landing gear.

Back up electrical generators (no need for APU generators in case of coupled approach)

Huge engines with high thrust, Dimensions, totally CAD planed,


94. What are the advantages of a wide-chord fan engine?

Unique wide chord, shroud less, hollow blades designed and developed by Rolls-Royce. These are manufactured by placing a 3D-machined piece of honeycomb material between two sheets of pre-machined titanium. At high temperatures a diffusion bond is formed between these three pieces of material such that the finished blade is effectively a single piece, hollow structure. This lightweight blade is then extremely strong with a leading edge that is robust and can resist damage due to foreign object impact. In addition, the wide-chord nature of the blade, centrifuges runway debris and dust into the by-pass duct reducing engine removals due to FOD (foreign object damage) by a factor of four when measured against conventional narrow blades. Fuel efficiency is another great characteristic. Wide-chord fan protects the engine against foreign object damage while latest-generation single crystal high-pressure turbine blades help to ensure that engines have the best on-wing life in the airline industry. Engines incorporating the wide chord blade have fan modules that are approximately 24% lighter and an engine which is 7% lighter (typically the Trent 800 engine as used in the Boeing 777). So the main advantages are best FOD & strongest fan ever built.


95. Outline takeoff performance planning on B777?

The max. permissible takeoff weight is the lowest of the corrected performance  

  • Climb limited weight
  • Improved climb limited weight
  • Runway limited weight

96. Explain the B777 anti / de-ice system?

The system contains:

  • Automatic ice detection
  • Engine anti ice
  • Wing anti ice
  • Flight deck window heat
  • Windshield wipers
  • Probe heat

97. How does a contaminated runway (ice, rain) or a tailwind affect your V1

(distance or speed)?

Distance to reach V1 for tailwind / contaminated runway is shorter.

V1 Speed is lower than the normal V1 speed.


98. How do you maintain obstacle clearance on B 777, what is the profile you fly?

Improved climb takeoff (Flaps 5) gives the highest takeoff weight to clear obstacles.


99. What are the limitations of spoilers ? How do you correct spoiler blowback?

Speed brake is extended when radio altitude is between 15’ and 800’, or when the flap lever is in landing position, or when thrust lever is not closed.

By extending or retarding the spoiler slow and gently.  


100. What are differential / non-differential spoilers?

Differential spoilers are slightly more sophisticated and will extend on one side in response to a roll demand and will retract on the other side. Non-differential spoilers will extend on one side in response to a roll demand but will not retract on the other side.

http://www.najaco.at/Books/indestructible_pilot/book/knowledge/knowledge_2.htm


101. What are the inputs of "Q" feel?

The "Q feel" ("Q" for dynamic air pressure) systems provide artificial feel forces to the pilot control yokes. This is because hydraulic powered controls mask high demands that may be applied by pilots inadvertently. You can compare it to a modern car’s power steering that changes it’s feeling as speed increases. The basic information comes from a pitot tube.

http://www.gaveasky.com.br/artigo36.htm


102. Why do engines have auto-ignition? How does it work?

To prevent engine flameout during rain /hail. When EEC detects an engine flameout, the respective engine igniters are activated. When engine flameout is detected, EEC energizes both igniters.    


103. What is wind shear? How is it detected ? Where do you find wind shear? Where do you find microburst?

Wind shear is any rapid change in wind direction or velocity. These wind variations can result from a large variety of meteorological conditions, temperature inversions, sea breezes, frontal systems, strong surface winds and thunderstorms. Two extreme types of microburst exists. One is the extremely dry environment in which moist convection is just barely possible, and the other is the extremely wet environment, which can produce microburst embedded in very heavy rain. A Low-Level Wind-Shear Alert System has been installed on the ground at more than 100 U.S. airports. Wind speed and directional sensors report to a central computer, and controllers can alert pilots in the ¢ vent wind shear is detected. But the systems cannot predict when wind shears are approaching. However, a ground-based radar (Terminal Doppler Weather Radar) system has been tested at Orlando, Fla., and Denver Stapleton airports and is scheduled to be stationed at more than 40 other airports by mid-1994. Even with such systems installed, however, airborne detection will still be needed because wind shear is a global phenomena and most airports will not have predictive, ground-based systems installed.

http://www.math.unl.edu/~jfisher/NSF_96/windshear.html

http://www.cimms.ou.edu/~doswell/microbursts/Figure_08.JPG


104. What is a mach trimmer? What is it used for?

In a flight control system, an automatic control sub-system which provides pitch trim of an aircraft as a function of mach number. The mach trim system provides automatic elevator quadrant displacement as a function of Mach number in the mach tuck         (nose down) region. Mach data from the air data computer is used to generate a servo position command signal. This signal is applied to the mach trim actuator. The actuator provides elevator pitch-up position to maintain the correct attitude when airplane mach tuck speed is attained. The mach trim actuator changes the position of the column neutral point without altering feel/force characteristics.

http://digilander.libero.it/andreatheone/dfcs.htm


105. What is an "assumed temperature"?

This is a way of reducing the take-off thrust to the minimum required for a safe take-off, thereby conserving engine life and hence reducing your chances of an engine failure. The RR Trend engines 884/892 are flat rated at ISA +30˚C. This means that they are guaranteed to give (at least) the rated thrust at the full throttle position when the OAT is below this temperature. Above this temperature, they will give less thrust because the air is less dense. On occasions when full thrust would be more than is safely required e.g. light aircraft, long runway, headwind etc. we can choose a thrust setting below full thrust by telling the engines (via the FMC) that the OAT is much higher than it actually is. This higher temperature is called the assumed temperature. Max. allowed reduction is 25% from max. takeoff thrust. (FAA)

http://www.b737.org.uk/assumedtemp.htm

http://www.aviation-industry.com/atem/EngineYB/Acrobat/eybdirturbos.pdf


106. What is the combustion cycle of a jet engine?

All jet engines, which are also called gas turbines, work on the same principle. The engine sucks air in at the front with a fan. A compressor raises the pressure of the air. The compressor is made up of fans with many blades and attached to a shaft. The blades compress the air. The compressed air is then sprayed with fuel and an electric spark lights the mixture. The burning gases expand and blast out through the nozzle, at the back of the engine. As the jets of gas shoot backward, the engine and the aircraft are thrust forward.

http://inventors.about.com/library/inventors/blhowajetengineworks.htm


107. What causes a jet-upset? How do you correct it?

Extreme attitudes, high / low speeds,

Immediate action items :

  • Push / Push the autopilot off and push yoke to unload any G’s.
  • Power / Increase if nose is high, decrease if nose is low.
  • Rudder / If nose is low, step on the sky.
  • Roll / Roll wings level before pitching up to horizon.

108. What is a service ceiling? An absolute ceiling?

Service ceiling: the maximum density altitude at which the best rate of climb will produce a 100 fpm rate of climb at maximum gross weight, gear up, flaps up, and maximum continuous power.

Absolute ceiling: the maximum density altitude which the aircraft can maintain or attain with two engines operating, maximum gross weight, gear up, flaps up, and maximum continuous power. As an aircraft climbs, VY decreases and VX increases. The density altitude where VY and VX meet is the absolute ceiling.

http://www.fergworld.com/cfi/pdf/Multi-engine_Instructor_Quick_Reference.doc

http://www.wordreference.com/english/definition.asp?en=service%20ceiling

http://www.wordreference.com/english/definition.asp?en=absolute%20ceiling


109. What is MCRIT?

Consider the flow past a standard aerofoil section. For a given flight Mach number (M), local Mach numbers at different points on the wing's surface will range from zero at the leading edge stagnation point to a maximum value somewhere on the upper surface. As M increases, the maximum local M on the upper surface will also increase until it eventually reaches M = 1 at the flight Mcrit. At any higher value of M there will be a region of supersonic flow produced on the upper surface, terminated by a terminal shock wave, leading to increased drag

http://www.rmcs.cranfield.ac.uk/aeroxtra/hsfapp.htm


110. What are the basic parameters of an aircraft electrical system?

Aircraft electrical components operate on many different voltages both AC and DC

However, most of the systems use:

115 V AC @ 400 Hz

28 V DC

26 V AC is also used in some aircraft for lighting

http://www.tech.purdue.edu/at/courses/at403/Aircraft_electrical_systems.ppt


111. What is a safety cell battery?

A safety cell battery is a battery which doesn’t leak.


112. Describe the construction of an engine generator?

The generator or IDG is fitted to the aircraft engine and takes a varying input speed from the engine, mechanically compensating for this varying speed to give a constant output speed to the Generator. An IDG integrates the Generator into the same unit as the CSD, giving a single, more compact unit.

http://www.tarel.com/constant_speed_drives.htm


113. What are your actions for a pitot / static blockage? An artificial horizon failure?

Pitot / static blockage causes unreliable data (speed, altitude, etc.). Use QRH Unreliable Airspeed table to determine Pitch and Thrust settings.

Use the standby horizon.  


114. During what phase of flight is lift the greatest?

Lift is greatest during takeoff. Highest weight of aircraft needs highest lift.

http://www.lerc.nasa.gov/WWW/K-12/airplane/smotion.html


115. Outline the change in the Center of Pressure as an aircraft increases speed

past MCRIT?

An aerodynamic center is at approximately the 25% chord point.  

However, as the aircraft moves into supersonic flight the up wash ahead of

the wing disappears (since no pressure waves move out ahead of the wing.)

As a result it is not surprising that the aerodynamic center and center of pressure,

both move back to the 50% chord point.

http://142.26.194.131/aerodynamics1/High-Speed/Page6.html


116. If you were loading an airplane to obtain max. Range, would you load it with a forward or aft C of G ?

Aft C of G.


117. If you were flying 076˚ heading to track 088˚, what is the heading required to maintain the reciprocal track?

HDG 280˚

WCA = 12˚ reciprocal track is 268˚ + 12˚ = HDG 280˚


118. If you are at 33.000 ft, OAT is -45˚, what is ∆T (deviation from ISA)?

ISA+6˚

33 x (-2˚) = -66˚+15˚ = -51˚


119. Tell me about IRS.

Platform with laser gyros not updated  System is self-contained.


120. How does differential GPS work?

A Differential Global Positioning System (DGPS) is a system designed to improve the accuracy of Global Navigation Satellite Systems (GNSS) by measuring infinitesimal changes in variables to provide satellite positioning corrections. Two or more receivers observe the same set of satellites, taking similar measurements that produce similar errors when positioned closely together. A reference receiver, placed at a known location, calculates its theoretical position and compares it to the measurements provided by the navigation satellite signals. The difference between the two values reveals the measurement error. The reference receiver then transmits a corrected signal to any number of receivers at unknown positions within the area covered by the DGPS. Accuracy of global satellite positioning is thereby increased from 15 meters to within a few meters. This technique compensates for errors in the satellite navigation system itself but may not always correct errors caused by the local environment when satellite navigation signals are reflected off of tall buildings or nearby mountains, creating multi-path signals.

http://products.thalesnavigation.com/en/products/aboutgps/dgps.asp


121. What are the various ETOPS categories?

Right now, qualifying twin-engine aircraft must be within 180 minutes flying time of an alternate airport in case a diversion is required, although an exemption of up to 207 minutes is allowed on some Northern Pacific routes. The ARAC proposal would add two more steps to this limit, up to 240 minutes and beyond 240 minutes. To use the new categories, carriers must have operational experience in the next lowest step.

http://www.aviationnow.com/avnow/news/channel_comm.jsp?view=story&id=news/cetop1217.xml

http://www.boeing.com/commercial/aeromagazine/aero_22/etops_story.html


122. What is the difference between a dry V1 and a wet V1? What does it change with respect to the screen height?

The wet V1 is lower than the dry V1.

The screen height of normally 35’ is reduced for a wet V1 to 15’.


123. How does cross-wind affect the critical engine?

The most hazardous crosswind takeoff situation regarding pilots and flight line safety is with the wind from behind the pilots and takeoff from right to left.

http://www.fly-imaa.org/imaa/hfarticles/safety/v9-4-64.html


124. If you fly in a region of volcanic dust discuss the procedures you would adopt, what is the hazards?

Avoid the area! If entered an area turn back by 180˚.

Engine over temperature, engine flameout, engine stall, cargo fire indication, smoke in the cabin, windscreen damage


125. If TOW is limited by an obstacle in the 2nd segment, what does it mean?

That the min. climb gradient  

  • of 2,4% for a 2 engine aircraft
  • of 2,7% for a 3 engine aircraft
  • of 3,0% for a 4 engine aircraft

is not reached.


See also

Tech Questions (Part 2)


Categories: Airline Interviews | Questions




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