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2011-11-28 08:51:58
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The technical part of the interview
Show Answers:

  1. What are the 2 different types of drag?
    • Parasite drag (zero lift drag): comprised of form / pressure drag, skin friction drag and interference drag and it varies directly with the speed.
    • Induced drag: caused by creating lift, associated with wing tip vortices. Induced drag decreases as speed increases.
  2. Why do modern jet aircraft have such large all moving horizontal tail planes?
    • To provide a balancing force for a large center of gravity range (CG changes with fuel burn during the flight)
    • To provide a balancing force for a large speed range
    • To cope with large trim changes as a result of configuration changes
    • To reduce elevator trim drag to a minimum
  3. Why are swept wings used? How does it help speed and C of G ranges?
    • To increase the critical mach number speed. This will result in higher mach cruise speeds.
    • Advantages: Higher mach cruise speeds & stability in turbulence due to poor lift qualities.
    • Disadvantages: Poor lift qualities, higher stall speeds, speed instability below VMD, wing tip stalling tendency
  4. How does a swept wing help speed and C of G ranges?
    • Speed: the velocity along the chord line of the wing is less due to the sweep. This delays the airflow over the wing from going supersonic. Reducing profile drag also increases the ability for higher speeds.
    • Due to the shape of the swept wing, and the ability to transfer fuel from or into the wing tips, it is possible to move the CG through a bigger range.
  5. What are the aerodynamic consequences of having under-wing mounted engines?
    • Increase in thrust will give a pitch up moment because the thrust line is located under the dragline
    • Intake efficiency is high: no turbulent air from the wings
    • Good accessibility for maintenance
    • Less complexity in fuel lines, air conditioning, anti ice and electrics
    • Close to CG: less effect on stability of the aircraft
    • Limited bypass size due to ground clearance
    • Sensitive to foreign object damage, because they are close to the ground
    • The weight on the wings helps to reduce the flutter and relieve wing bending
  6. How does it affect the airflow over the wing?
    At high angles of attack the airflow over the wings could be disturbed by the engines.
  7. What differences do we have when mounting engines under the wing instead of at the aft fuselage?
    • Thrust line closer to the longitudinal axis gives less yawing moment in case of asymmetric thrust (aft engines)
    • Aft mounted engines will provide a complete clean wing design
    • Ground clearance of aft mounted engines is greater, makes it less sensitive to FOD
    • Intake air can be affected by turbulence from the wing with aft mounted engines
    • The fuel line design is more complex at the aft mounted engines
  8. What are slats/ slots? Why are they used?
    High lift devices at the leading edge. They increase the wing’s chamber area and MAC, thereby increasing the lift coefficient, which reduces the stall speed. (They form a slot where air can pass trough at high angels of attack. This way they restore the kinetic energy of the boundary layer)
  9. Dutch Roll – how is it caused?
    Dutch roll is induced by a yaw input on a swept wing aircraft. This causes the outer wing to travel faster and become straighter to the relative airflow. This will create more lift on one side of the A/C and will make the aircraft bank. This will continue until the outer upward moving wing stalls and drops, causing a yaw to the stalled wing and is being repeated in the other direction.
  10. Yaw damper – functions
    A yaw damper prevents Dutch roll on a swept wing aircraft, and coordinate turns. It’s a gyro system that is sensitive to yaw and feeds a signal into the rudder, which applies opposite rudder to the yaw before the roll occurs.
  11. What is Vmca/ Vmcg? How can it be changed?
    • VMCA: The minimum control speed in the air for a multi engine aircraft. To make sure that you still have directional control with the rudder after an engine failure in the take-off and climb out configuration.
    • VMCG: The minimum control speed on the ground for a multi engine aircraft. At and above this speed it is possible to maintain directional control of the aircraft with the rudder after failure of an engine.
    • An aft C/G position requires a higher VMCG/A. With an aft CG the rudder moment arm will be shorter, and therefore the turning moment is less for a given airspeed. So using a different CG position you can change the minimum control speed.
  12. What is Mcrit, and why is it a problem flying faster?
    • Mcrit is the mach speed at which the airflow over a wing becomes sonic. Characteristics are: mach buffet (shock waves), increase in drag (breakdown of airflow over surface), nose down change attitude and possible loss of control.
    • Flying faster than the critical mach number will cause a rapid rise in drag, causing the aircraft to lose lift due to not enough power to maintain its speed.
  13. What is mach tuck, why and how do we prevent from happening?
    Nose down pitching moment as an AC passes its critical mach number. The instability is created by the rearward movement of the CP, behind the CG, which induces the AC to pitch down.
  14. What is a vortex generator? Why are they used? Other than a wing where else might they be used?
    Small vanes that create a slight disturbed airflow. They are used to reduce the spanwise airflow over the wing which helps to maximize the effectiveness of control surfaces. They are also used at the inlet of an APU, to deliver denser air which is of a slower velocity.
  15. Difference between flap 30 and flap 40 landing
    Flaps 30: less drag, higher speed, longer roll out. Flaps 40: more drag, lower speed, shorter runway possible.
  16. Explain reduced take-off thrust and how does it influence the take off?
    • Take off thrust setting required for the aircraft’s actual take off weight. It is a value that meets the aircraft’s take off and climb performance with one engine inoperative. (based on a assumed/flexible temperature)
    • It is used to protect engine life and reduce noise generated by the AC.
    • The take off run will be longer and the climb gradient will be shallower.
  17. What happens to the ground roll when you take off with more flaps?
    The ground roll will be shorter due to higher CL, the climb gradient will be shallower due to increased drag.
  18. Explain coffin corner.
    It is the absolute ceiling of an aircraft. It is at the speed where mach buffet and pre-stall buffet coincide. For a constant mach number the IAS increases with increasing altitude due to a decreasing LSS.
  19. What saves more fuel on landing: High or low flap setting?
    A low flap setting because of the lower drag. But it does require a longer runway because of the higher approach speed.
  20. The effect of wind on your descent
    • Tailwind: late TOD point
    • Headwind: early TOD point
  21. The effect of weight on your descent
    The aircraft is restricted to a maximum airspeed in the descent. The heavier the aircraft, the shallower the descent. Heavier aircraft have a bigger momentum and this weight driven momentum will produce a greater speed in a vertical dive.
  22. Engine fire drill and who do you inform
    • Air traffic control
    • Cabin crew
  23. Why would we have bleed valves on the engine?
    • To provide bleed air for auxiliary systems like air conditioning, cabin/cargo heating, engine cooling, accessory cooling, engine and wing anti ice systems.
    • To regulate the correct airflow between different engine sections.
  24. When does a cross bleed air start happen?
    When the APU is unserviceable.
  25. List the uses & purposes of bleed air
    Air-conditioning, wing anti-icing, water pressurization, hydraulic reservoir pressurization, cabin pressurization,
  26. Explain how bleed air is used in the water system in the toilets of a modern jet?
    While airborne, the aircraft uses bleed air to pressurize the water system. Differential pressure forces waste from the toilet bowls into the waste storage tank, and discharges wastewater towards anti-iced drain masts.
  27. What type of engine does Tiger Airways have on the A320? Do all the aircraft have the same engines?
    • International Aero Engines V2500 and V2524
    • Proven track record for reliability and efficiency
  28. How does a Jet engine work?
    • Thrust = air mass x velocity
    • Suck: Air is sucked into the engine intake where it loses velocity and therefore increases its pressure energy as it passes through the divergent duct;
    • Squeeze: The air is compressed by the low pressure compressor and high pressure compressor
    • Bang: The total energy is increases by the combustion of fuel (heat energy);
    • Blow: The expanding gasses accelerate over the turbines to the outlet convergent duct.
  29. What is the difference between a turbofan and turbojet engine?
    At a turbofan engine not all the air moved by the fan goes into the combustion chamber. A portion of the air flows over the engine itself (bypass air).
  30. What is the difference between a gas turbine and a jet engine?
    A gas turbine engine has a turbine driven compressor that produces thrust at low speeds.
  31. What do you know about turbines in a fan engine?
    The turbines in a fan engine are driving the compressors and the fan. A turbine connected to a compressor is called a spool. Turbofan engines normally have 3 spools, the fan spool (N1), the intermediate pressure compressor (N2) and the high pressure compressor spool (N3)
  32. How are the turbine blades cooled?
    • Thermal barrier coatings
    • Cooling air from the compressor
  33. What are the possible advantages of a high bypass engine? (5:1 or 6:1)
    • Better fuel efficiency (higher mass, lower velocity produced)
    • Reduced engine noise (bypass duct & low speed exhaust)
    • Contamination is centrifugally discharged
  34. What produces the majority of the thrust?
    In a high bypass jet engine the mass of air produces the majority of thrust. Thrust = mass x velocity. In a high bypass engine a large mass of air is driven backwards at a low velocity.
  35. What could be the possible uses of filtering hot air from the engines?
    The hot air can be used for the anti ice system and cabin heating system.
  36. Why pressurise the hydraulic system?
    To prevent cavitation, which causes wear of the metallic surfaces of the system.
  37. What is an INS and how does it work?
    Inertia navigation system: on board, self contained system, that provides continuous information about the aircraft’s position. The system measures the aircraft’s inertia movement from an initial position. The components are accelerometers, gyroscopes and a position computer.
  38. How do you recognize an engine surge and what are the causes?
    Reverse airflow in the engine, indications are a loud bang, vibration and temperature rising.
  39. What is FADEC and does the A320 have FADEC?
    • FADEC = Full Authority Digital Engine Control. It is a system that automatically controls the engine functions (start procedures, monitoring, fuel flow, ignition system, power levels). By using the engine functions as efficient as possible the fuel efficiency and lifetime of the engine is increased. It also gives a reduction of crew workload.
    • The A320 has FADEC for thrust control.
  40. How many hydraulic systems does an Airbus have?
    3 hydraulic systems: blue, green and yellow. Each system has its own hydraulic reservoir. The system operating pressure is 3000 psi.
  41. What are the functions of spoilers?
    • Assisting the ailerons for roll control
    • Air speed brakes to slow down the aircraft in the air
    • Ground lift dumpers, to transfer the full weight of the aircraft on the brakes on landing / rejected take off for optimal braking efficiency
  42. Explain TCAS
    • Traffic collision avoidance system, provides traffic information and maneuver advice between aircraft if their flight paths are conflicting TCAS uses the secondary surveillance radar transponders of aircraft to plot their positions and relative velocities.
    • Direction finding aerials determine relative bearings, and distance is calculated by time delay between transmitted and received signals. Warnings are on initially and collision threat basis, advised actions are in vertical avoidance only.
  43. What are the advantages of Fly-by-wire?
    • Fly by wire: The movement of flight controls are converted into electronic signals transmitted by wires, and flight control computers determine how to move the actuators at each control surface to provide the ordered response.
    • Lighter: mechanical control systems are heavy
    • Safety: stabilizes the aircraft automatically in changing aerodynamic conditions. The signal from the control column is checked by the computer, which calculates the movement of the control surface actuator.
  44. High lift devices fitted to the airbus
    • Trailing edge flaps: single slotted
    • Leading edge slats: one inboard slat and four outboard slats
  45. What happens if you increase the engine power by moving the throttles forward?
    With engines mounted under the wing the higher dragline will cause a nose-up pitch tendency as thrust is increased.
  46. Name 5 conditions that have an impact on take-off conditions?
    • Aircraft weight: high weight = long take off roll
    • Flap setting: low flap setting = long take off roll = high climb gradient
    • Wind speed and direction: tail wind = long take off roll
    • Density altitude: high density altitude = low density = long take off roll
    • Humidity: high humidity = long take off roll
    • Temperature: high temperature = long take off roll
    • Runway condition = wet = long take off roll
  47. How do you calculate pressure altitude?
    • 1mb: 30 feet
    • Calculate difference between regional QNH and 1013mb
    • Convert pressure difference into height
    • Add or subtract from pressure altitude whether
    • Remember: when pressure is higher than standard, pressure altitude is lower than field elevation.
    • Example: Airport elevation 2340ft, QNH 1034mb. 1013-1034 = -21
    • -21 x 30 = -630. 2340 - 630 = 1710ft.
  48. Name 3 ways to brake the aircraft in a rejected take-off.
    • Wheel disc brakes
    • Reverse thrust
    • Speed brakes
  49. How do you know what the aircraft is going to do?
    • Trend vectors
    • Flight Mode Annunciator
  50. How can you minimize the fuel burned on a trip?
    • Always adhere to the SOP’s
    • Fly at the optimum altitude where possible
    • Request direct routing (shortcuts)
    • Do not take too much fuel for the trip
  51. To what approach category is an Airbus 320 certified and what ILS category is it capable to land off?
    • Approach category = C (Vat = 121-140kts) (speed at threshold based on 1.3 times stall speed in the landing configuration at max certified landing mass). The A320 Vref is 134 KIAS at MLM 64.5 tonnes.
    • Depending on the qualifications of the crew the A320 is capable of landing from CATIIIB approaches. DH = less than 50ft, RVR at least 75m touchdown / midpoint
  52. What options do you have when you have a gear failure?
    • Extend mechanically: isolate landing gear hydraulics, unlock gear doors and allows gravity to drop the gear into extended position.
    • Locking springs help to crank the main gear into locked condition, and aerodynamic forces assist in locking the of the nose gear.
  53. What de-ice/ anti-ice equipment does the Seneca have?
    • Electro thermal props
    • Pneumatic boots
    • De-icing fluid (for cockpit windows)
    • Pitot tube / stall warner heater
    • Window heater
  54. What de-ice/ anti-ice equipment does the A320 have?
    • Leading edge outboard slats heating by hot air
    • Engine air intakes heated by hot air
    • Flight compartment windows by electrical heating
    • Sensors, pitot probes and static ports by electrical heating
    • Waste water drain mast by electrical heating
  55. What navigation equipment does the Piper Seneca have?
  56. What is the range and endurance and cruise speed of a Seneca?
    • Range: 500 miles
    • Endurance: 4 hours
    • Cruise speed: 140 knots
    • Stall speed: 66 kts clean, 60 kts landing configuration
  57. How long does it take for an IRS to align in the A320
    Up to 10 minutes
  58. Why do we have turbofans on Airbus?
    • Powerful engines
    • Very efficient engines on high cruising altitudes
  59. What sort of flaps does the Airbus have?
    A319 & A320: single flap surfaces
  60. What is the difference between a 737/ A320?
    • FADEC
    • Fly by wire
  61. Do our aircraft have anti-icing equipment on the tail?
    No, only on the outboard areas of the wings, engine air intakes, cockpit windows, pitot probes, static ports and waste water drains. Not on the tail because ice on the tail wouldn’t affect the aerodynamic performance of the aircraft.
  62. What could you do to minimise the risk of icing?
    • Use anti-ice systems as needed
    • Avoid flying through CB’s
    • Check weather before flight
  63. What engines does a Seneca have?
    • 6 cylinder horizontally opposed
    • Air cooled
    • Turbo charged
    • 200 brake horse power
    • Wet sump oil system
  64. Do you know the time and distance separation minima?
    • Medium departing behind heavy: 2 minutes (3 minutes from intermediate position on the runway)
    • Medium landing behind heavy: 5 miles / 2 minutes
  65. Relating to wake turbulence what is the separation distance required for a medium jet approaching/landing after another medium jet?
    3 nautical miles
  66. What is RVSM?
    • Reduced vertical separation minima.
    • The reduction of the standard vertical separation required between aircraft flying at levels between FL290 and F410 from 2,000ft to 1,000ft. This will increase the number of aircraft that can fly safely in a particular volume of airspace. Because of the increased accuracy of the altimeter and the combination with air data computers & autopilots this separation could be reduced to 1,000ft.
  67. Squawk code hijack & radio failure.
    • Hijack: 7500
    • Radio failure : 7600
  68. How do you calculate the TOD
    • Flight level – airfield elevation / 300
    • Add 2 nm to get into descent, and add 4-6 nm to slow down to 250 kts.
  69. If you don’t have enough track miles, how do you solve that problem?
    • Use speedbrakes
    • Request extra track miles from air traffic controller
  70. Why would we circle to land, why not just fly straight in?
    If the runway in use is not aligned within 30 degrees of the final approach course of the instrument approach procedure, the approach requires visual manoeuvring of the aircraft in the vicinity of the airport. The runway in use lack instrument approach procedures or their approaches cannot be used (navigation aids out of service, traffic considerations)
  71. Describe the four climb segments. (at a constant V2 speed)
    • To make obstacle calculations predictable the aircraft is presumed to be flown through several reconfiguration segments on take-off. Calculations are based on engine failure at V1.
    • First segment: end of TOD – Gear retraction finished (TOD ends at 35ft screen height – dry runway, or 15ft screen height – wet runway)
    • Second segment: end of first segment – to 400ft / 1000ft AGL (safe height)
    • Third segment: level flight, acceleration during which the flaps are retracted to flaps up speed climb speed
    • Fourth segment: end of third segment – to 1500ft with flaps up and max continuous thrust.
  72. You are told to hold at a waypoint. How long or how far before the waypoint should you reduce to you holding speed.
    You have to be at your holding speed, 3 minutes before reaching the holding fix.
  73. What is the range of a VOR at 32000 ft?
    Up to 100 nautical miles
  74. What are the stages of a thunderstorm?
    Building (updrafts), mature (up & downdrafts, most hazardous) and dissipating stage (sporadic showers).
  75. How can you tell a thunderstorm is in its dissipating stage?
    • Dominated by downdrafts, which carry cool air to the ground (downburst)
    • Sporadic showers (inflow air is prohibited by the downburst)
    • Potential virga & windshear (outflow from downburst)
  76. What is the Dew Point?
    The temperature to which a parcel of air must be cooled, for water vapour to condense into water. A high relative humidity indicates that the dew point is close to the current temperature.
  77. What is virga/ microburst?
    • Virga: A streak of precipitation that evaporates before reaching the ground. It removes heat from the air underneath, which can cause the pockets of air descending rapidly, creating a microburst.
    • Microburst: localized column of sinking air, producing divergent and straight line winds at the surface, causing low level windshear
  78. From TAF/METAR –BR, GR and FU
    Light Mist, Hail and Fume
  79. Tell me about adiabatic lapse rates, what are they? What are the assumed values?
    • The rate of decreasing temperature with height
    • ELR: environmental lapse rate, the rate of decreasing temperature in the standard atmosphere (ISA): 1.98⁰C / 1000ft
    • SALR: saturated adiabatic lapse rate, the adiabatic change in temperature for saturated air as it rises. The parcel of air consists of 100% relative humidity and its temperature is reduced to the dew point temperature. 1.5⁰C / 1000ft.
    • DALR: dry adiabatic lapse rate, the rate of decreasing temperature in a dry or unsaturated parcel of air (less than 100% relative humidity). The temperature of this parcel is higher than its dew point. 3⁰C / 1000ft
  80. Fohn wind
    Moist air is pushed up a hill or mountain by the wind (windward side). The air will cool adiabatically and the water will condense and form rain. The dry air at the lee side of the mountain will heat adiabatically, resulting in a higher temperature than at the windward side of the mountain.
  81. What would you do if you flew into unexpected weather?
    Fly the aircraft first.
  82. Why do I want to work for easyJet
    • Well known and established airline in Europe which is available for almost everybody because of their low fares.
    • Very ambitious company that is growing rapidly, which gives the employees the opportunity to grow in the company as well.
    • Operating short haul routes.
    • A very easy and therefore synoptic work process.
    • Flying to convenient airports all around Europe.
  83. Tell me a bit about easyJet.
    • Established in 1995, founded by Stellios Haji-Ioannou
    • Headquarters: London Luton
    • CEO: Carolyn McCall (started 1st of July 2010)
    • Flying short haul routes with over 200 aircraft to 29 countries in Europe
    • Vision = turning Europe orange
    • Over 7300 employees
    • Served over 50 million passengers last year
    • Low cost carrier business model:
    • Single passenger class with no optional onboard equipment;
    • Single type of new, fuel efficient aircraft (reducing training and maintenance costs);
    • Development of one or more hubs to maximise destination coverage to defend their market;
    • Simple fare scheme, booking via internet website (90% of bookings);
    • Fast turnaround times;
    • Simplified point to point routes (no transfer services)
    • Charges for extras such as hold luggage and priority boarding;
    • Using mobile stairways to board and offload passengers.
    • Established on serving the leisure market, more focus is turned on the business passengers by offering services like free transfers on an earlier flight without charge
    • Innovative: nano technology (coating), tech insertion engines, developing easyHolidays.
    • Marketing strategy:
    • Price: low fares
    • Product: easy, transparent, recognizable
    • Place: flying from convenient airports in populated areas
    • Promotion: visit Britain, nectar
  84. What does Stelios think of all the things going on (talk about the agreement EZY and Stelios have: 75% income from the flights and 25% from others; hotels, cruise, car rentals and that the income from others is increasing and is more than the 25% now)
    In 2010 Stelios announced that he disagrees with the rapid fleet expansion of easyJet. According to him the reason to flatten out the fleet expansion is because the profit margins are too low and are not growing, giving the shareholders no value for their investments, which are used to expand the fleet.
  85. Roughly how many routes does EZY have?
    Approximately 560 routes
  86. Roughly how many planes does EZY have and what types
    Approximately 200 aircraft, A319 and A320
  87. How much flight crew do you think is employed by EZY
    • Pilots: approximately 1900
    • Cabin crew: approximately 4300
  88. Largest 3 bases?
    • London Gatwick
    • London Luton
    • Milan Malpensa
  89. What do you think are easyJet’s strengths?
    • Low cost business model keeps the fares low, which attracts passengers
    • Safe and efficient way of operating the flights
    • Offer high quality service at competitive prices
    • Flights available from airports located close to populated areas
    • Number one presence on top 100 routes
    • User friendly website
    • Recognized as leading brand in UK travel industry
    • Embrace their environmental responsibilities and keep these responsibilities as a priority in future strategies
  90. What are easyJets weaknesses:
    • Congestion on bases will affect punctuality
    • On time performance results (getting better)
  91. If you had to choose one thing about easyJet that draws you to the company, what would it be?
    The variation the company is offering. A very wide route network, bases in different countries around Europe, staff from different countries. This variation in combination with a rapidly growing company with a lot of future opportunities makes me enthusiastic to work for this company
  92. How has Easyjet set itself apart from other airlines?
    • By it’s network
    • Flying from convenient airports at convenient times as a low cost carrier
    • By its friendly and professional service
    • By being involved in activities to reduce emissions
  93. Why is our culture different from other companies
    • Easyjet culture: flat hierarchy, be yourself, remote working, fun, enjoyment.
    • The flat hierarchy is a sign that easyJet thrust their employees by what they are doing. This will give the employees confidence and that will result in excellent customer service.
    • Easyjet stimulates their employees feeling relaxed while their working by allowing them to be theirselves in their job. No ties are allowed at offices, offices are open and remote, and having fun is very important while working for easyJet.
  94. What would your preferred base be?
  95. What is the easyJet ethos (character)?
    • Easyjets ethos is expressed through 5 values:
    • Safety
    • Teamwork
    • Pioneering
    • Passionate
    • Integrity