V1 is "go / no-go" decision speed. If an engine failure occurs prior to V1, the pilot in command, i.e., captain, will abort the takeoff. Should an engine failure occurs at or after V1, the aircraft is committed with its takeoff roll. V1 is calculated for each takeoff to ensure balanced field length. This means that for an engine failure at V1, it will take the same distance to continue the takeoff as it will to abort. The decision to abort prior to V1, or continuing the takeoff roll thereafter, is the option that'll take less distance. V1 is most heavily influenced by runway condition & aircraft configuration.
Vr is a velocity post V1 and is the aircraft speed calculated for when the pilot can apply control inputs whereby the nose of the aricraft can rotate approx. 3o/sec pitch for about 3 sec. At this point the aircraft should be virtually at V2.
V2 is the velocity at best angle of climb attitude with engine out condition. At V2 the pilot flying will apply an additional minor control input in order to rotate the aircraft exactly to the optimum climb attitude and the aircraft should begin to "fly". Once the aircraft is positively airborne, the pilot flying will adjust pitch so as to maintain V2 as the aircraft climbs to acceleration height.
Vr & V2 are dependent upon environmental conditions and aircraft configuration.
Once acceleration height is reached (usually at 1000' AGL above the airfield), the pilot not-flying retracts the landing gear and at V2+10kts flaps are retracted. The pilot flying adjusts control inputs in order to obtain best climb speed. This velocity is maintained until level-off altitude is obtained.
An old joke among pilots is that the second engine is there to fly to the scene of a catastrophic landing. When engine failure occurs shortly after takeoff, two problems exist simultaneously: low airspeed and low altitude. At low airspeeds, it's tough to maintain control of a twin with full power on one side of the aircraft and lots of drag from a windmilling engine on the other (not neglecting torque imbalance issues). The airplane will yaw and roll violently, and the pilot must immediately apply aggressive control movements to maintain control. And that doesn't even address the very real issue of stall avoidance.
Airliners always have adequate single-engine climb performance. For each takeoff, pilots examine performance data specific to each runway and incorporate temperature, wind, and aircraft configuration into each of the critical velocity calculations. The runway specific performance data yields maximum weight for takeoff assuring adequate performance in the "worse case scenario" - that is, an engine failure right at V1. Assuming that the performance data is accurate, aircraft climbout is guaranteed in so far as the flight crew follows proper engine-out procedures should that occur. Pilots have the benefit of realistic simulation training for such situation, and morover, that the non-flying pilot can take care of checklists, radio calls, etc, while the flying pilot concentrates on maintaining control of the airplane.
If an engine malfunction occurs at or post V1, the aforementioned takeoff procedure is adhered to up until acceleration height is reached. No checklists are conducted until then however; the flight crew's main priority is to concentrate on keeping the airplane under control and climbing to acceleration height.
Upon reaching acceleration height, the aircraft is leveled out, flaps are retracted at V2 + 10 kts, and accelerate to best climb speed before resuming the climb at that airspeed. Only then does the pilot flying call for the engine failure checklist. This emergency checklist leads to several others ("engine failure cleanup items" and "single engine approach and landing"), which are performed in between talking to ATC, dispatcher (and possibly maintenance control), coordinating the arrival with flight attendants, and perhaps a PA announcement to the passengers.
Each runway has a "turn procedure" assigned for use in the event of an engine failure. Many of these are rather simple and do not require a turn below acceleration height. Where obstacles present problems to slowly climbing aircraft, however, a complex turn procedure may be in force. Most turn procedures have textual descriptions, although a few are sufficiently complex so as to require their own Jeppesen chart. Here's the turn procedure for runway 10L at Portland: "Climb via PDX radial 085 until reaching PDX DME 7.8, or IVDG DME 7.6, then turn right heading 280. Acceleration height 1030'." In this case, you'd make the turn to intercept the PDX 085 radial at 50 feet (!).
After that, it's time to land, smile at the passengers as they deplane, and then go drink some beer.
Wow. Fantastic explanation, thanks. Did I at least do OK considering I’m not a pilot, just a flight sim geek and longtime computer airplane nerd? :)
So if the plane was able to take off on one engine, even at a near-maximum load (~170 onboard), I wonder what caused it to stall out and crash if there was an engine failure. They’ve almost certainly recovered both the CVR and FDR.
}:-)4