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If an engine fails on take off, will the pilot abort the takeoff or continue and how do they make that decision?

You have lined up on the runway, made the last checks and received the clearance to take off. It is time to release the brakes and smoothly increase the power after a few seconds the aircraft starts moving, probably you will take off without any unusual events in the middle but in any case, during the take-off roll, you have to think constantly about what would you do in case of an engine failure or any abnormality but you should not let that possibility stress you because you have a take-off to complete but a part of your brain should take a look at the different procedures to abort the manoeuvre in case it was necessary.

Of course, how you will react will depend on the moment in which the abnormality in this case an engine failure occurs. If you have barely initiated the take-off roll, you can abort easily, just stop the plane with the brakes while maintaining the runway centerline. The problem to decide if abort or continuing the take-off comes at higher speeds where a stop could not be possible in the remaining runway to help you decide in the heat of the moment a decision speed or V1 has been implemented

  • V1 -> Takeoff Decision Speed -> V1 is the maximum speed during takeoff that will allow the aircraft to stop on what remains of the runway in case of an aborted takeoff. It is essential to know that V1 is not a fixed value and its calculation is a matter of many factors such as the weight of the aircraft, the airport elevation, the existence of any slope on the runway, and the presence of precipitation or ice.

The closer your speed is to V1 at the moment of the failure, the less possibility to successfully stop the aircraft on the remaining runway. Once V1 is reached, the option to abort the take-off is eliminated because at higher speeds is much safer to continue the take-off, your speed is still increasing and soon you reach VR (rotation speed), it is time to pull back on the yoke and leave the ground.

  • VR -> Rotation Speed -> is the speed at which the pilot begins to pull back on the control column to cause the aircraft nose to pitch up, after which it will leave the ground. It cannot be less than V1

Congratulations you are in the air but your work is not over yet, you have to make sure you reach V2 (takeoff safety speed)

  • V2 -> Takeoff Safety Speed -> At this speed, the aircraft may safely climb with one engine inoperative.

In all emergencies in aviation a proper order of priorities is set to handle the situation safely: Aviate, Navigate and Communicate. The first one as you can see is Aviate which means maintaining the aircraft under control. The failure of an engine causes three problems that you have to counteract:

  • Reduced thrust
  • Increase drag
  • Asymmetric thrust

The reduced thrust and increased drag paired with the full power generated by the other engine creates a thrust asymmetry which causes the aircraft to roll to the side of the broken engine. To stabilize the flight three things must be done:

  • Pitch down to maintain speed always above V2
  • Press the rudder pedal in the direction of the live engine (dead foot – dead engine) so the aircraft remains coordinated
  • Ailerons should be used to raise the dead engine wing to maintain the aircraft in a wings-level attitude

These are the first steps to remaining in control of the aircraft during the first moments after lift-off but there are more things to be done. retract gear, retract flaps, secure the engine…etc. All these steps must have been previously discussed in the take-off briefing, for example in an A320:

  • In case of failure after V1:
  • Continue take-off, no actions before 400 ft AGL (Above Ground Level) except gear up
  • reaching 400 ft AGL, ECAM actions (Electronic Centralised Aircraft Monitoring (ECAM) is a system that monitors aircraft functions and relays them to the pilots. It also produces messages detailing failures and lists procedures to correct the problem)
  • Reaching Engine Out Acceleration Altitude (the altitude that the aircraft transitions from takeoff speed to climb-out speed): if the engine is secured, level off, accelerate and clean up. Otherwise, continue climbing until the engine is secured

This is an example for a modern airliner but for a smaller multi-engine of the general aviation category would be more simple but will include similar information about altitudes, speeds when to retract gear, flaps .. etc. Also in these briefings the second priority is usually discussed, Navigate. Where you are and where you want to go and how you will reach there. Depending on the situation, it is possible to do an immediate return, or maybe it will be necessary to ask for radar vectors to the ATC to align us to the landing runway.

This takes us to the last priority, Communicate, also this part follows a predetermined standard. When an aircraft is in a dangerous situation, for any circumstance, the pilot will inform the ATC using the radiotelephone distress signal “MAYDAY”, repeated three times, followed by the distress message, which will contain as many of the following elements as possible if possible in the next order:

  • The name of the dependency being called
  • Identification of the aircraft, by its callsign.
  • Nature of the dangerous condition.
  • Present position, level or altitude and heading.
  • Intentions of the aircraft.
  • Example -> MAYDAY, MAYDAY, MAYDAY, Madrid Approach, IBE6165, five miles on course to PARLA, flight level 110, complete failure of the left engine, we request vectors to return to the airport.
Source: Quora
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