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Rotation Speed

by Darren Smith, CFII/MEI
PocketLearning, August, 2007

One of those little airmanship issues I've seen in students is how / when rotation occurs. What is rotation speed (Vr)? It's the point at which the pilot uses the elevator to pivot the aircraft's longitudinal axis skyward. Its the magical transition that every airplane goes through as it takes flight. I've seen the good and the bad, the elegant and the ugly. For most small aircraft, full engine power is often used. For jet aircraft, there are occasions when less than full power is used and this is called a FLEX takeoff. Sometimes flaps are used, sometimes required, especially common in jet aircraft. In either case, that adds surface area to the wing and lowers stalling speed.

For most general aviation aircraft, full power, acceleration to rotation speed, and a 5 to 10 degree pitch up takes an airplane skyward at a safe speed. When things go wrong, its usually an engine failure or pitching up too far. How far is too far? Answer: when the aircraft's critical angle of attack has been exceeded -- leading to a stall. When that happens, control effectiveness becomes mushy and the aircraft will either settle back to the surface or nose over straight into the ground. In the last 5 years, accidents at some major airshows around the country, the cause of the accident was stall spin. Its one of the top 3 killers in general aviation.

I've seen way more than my share of takeoffs where the pilot jerks the airplane into the air. I often tell folks who show me such ugly takeoffs that the airplane will fly when its good and ready. Only a little encouragement is all that is needed in most light general aviation aircraft to get it to fly -- we'll call that pre-rotation. A slight pitch up at Vr will cause the resulting takeoff to be elegant and well within safety parameters.

The next thing I see can best be described as the "pull and pray" method of taking off. Folks will pull the yoke back quite far and pitch the nose so high, you could easily stall or collide with something you didn't see. The reasoning that some instructors teach this is because if you have an engine failure, you'll have some altitude to react. While this is true, I dont see "engine failure" in the top 3 killers in general aviation, but stall/spin is there. I always teach students to put the nose on the horizon and climb out at a safe airspeed / flight attitude.

The next little trick some folks pull is to yank the gear up as soon as they break ground. This is clearly wrong. Before you put the gear up, be sure to remind yourself, "positive rate, no more usable runway, gear up." What? Yes, its not just positive rate then put the gear up. For the general aviation aircraft, you should also determine that you have no more usable runway. If the engine quits, you'll be able to set the airplane down on the remaining runway. Obviously you should also establish a stabilized positive rate of climb as well. In light twins, you might want to retract the gear just a half of a moment earlier as its a significant amount of drag in engine out emergencies.

Pre take off briefing

Every pilot should perform a pre take off briefing reviewing critical factors. Those considerations include:

Should I be making this flight? Personal Minimums Checklist(download)
Crosswind conditions
Runway factors, length, surface, slope, obstructions.
Fuel pump? Some require it some prohibit it.
Review aircraft performance, length needed, density altitude
Proper checklist
Engine failure plan with runway remaining
Engine failure plan in departure area
Collision avoidance
Multi-engine go / no-go factors

Callouts & Takeoff

If you're flying with another pilot, you should make a series of callouts on the takeoff roll. They go like this:

[Before holding short, perform clearing turn to determine pattern traffic]
"Nothing on downwind, base (either side), final, and (the other) downwind"
[Proceed to hold short line -- obtain clearance as needed]
[Before entering the runway] "Nothing on final, nothing coming down the wrong way."
[Enter the runway, make radio call as you are moving]
[Line up on centerline, quickly perform lineup checks]
[Advance power to at least 75% power] "Oil temperature and pressure good."
[Continue to advance power and release brakes]
[Observe airspeed and tracking of runway centerline] "Airspeed alive"
[Call out the airspeed 1/2 way between 0 and rotation speed] "30 knots, 50 knots, Rotate"
[Slowly encourage the aircraft to fly with back pressure and when flying, pitch nose to horizon]
"Springfield traffic, Skyhawk 44E departure leg runway 27 departing to the north, Springfield"

Always consult your POH for the procedure for your aircraft

Other Stuff to Remember

Don't waste any time on the runway, get on and off the runway as quickly and safely as possible.
Runway behind you is wasted.
"...commence turn to crosswind leg beyond the departure end of the runway within 300 feet of pattern altitude." -- AIM 4-3-3

Coming soon in part two of this series... examples of what happens when you pitch up too far or retract the gear too soon after take off.

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