Timed-Out Takeoffs

Your decision to abort, return or continue if theres a problem may get complicated by a clearance void time. It shouldnt.


I’ve not found any published data on the subject, but after years or reading accident reports I’ve formed the opinion that pilots making takeoffs that will be followed by a flight on an IFR flight plan may unconsciously add a little more “I gotta go come hell or high water” attitude than their normal, Type A, mission-completion orientation to the decision-making process.

There is no such thing as an emergency takeoff, yet I see accident reports of pilots launching into weather that is well below what’s needed for the approach back into the airport and then losing control not long after punching into the clag despite the fact that the weather was forecast to become solidly VFR within a couple of hours (and did). I have looked at crashes after takeoff where the airplane was well over gross, the runway was plenty long enough to abort the takeoff even after getting into the air, yet the pilot, on an IFR flight plan, pressed on. Not surprisingly, he discovered that once he pulled the airplane out of ground effect, the airspeed started deteriorating and the airplane either sank back to the ground or ran into an obstruction. It can happen like this.

The Scenario

Your fishing trip was just about perfect. You and your three buddies limited out and filled the coolers, which are now packed with ice for the flight home. Fuel was surprisingly inexpensive at the resort’s airport, so you filled the tanks of your trusty Cherokee Six. The high summer haze has cut visibility and you’re going to be flying into the sun. Out of an abundance of caution, you filed IFR.

It’s hot, so you got your clearance via cellphone on the terminal ramp before boarding everyone—you didn’t want to sit there idling while the passengers steamed. The void time is 10 minutes away, plenty of time to strap everybody in, crank the big Lycoming, taxi out and get in the air at this little airport.

Turning onto the parallel taxiway, you see there’s an airplane at the end. You figure it’s no big deal; he’ll complete his run-up and take off before you get there. He doesn’t. Now your void time is three minutes away. You call the guy in front on CTAF to see if he’ll just taxi onto the run-up pad and not block the taxiway. No answer.

Two minutes to void time. You’ve got room to swing around behind the knucklehead—so you add power, make a 180 on the taxiway and hustle down it to the intersecting taxiway you passed several hundred feet back. Turning onto it, you see that idiot is still sitting there and no one is on final. Just over a minute to void time—not enough to back taxi—so you firewall the throttle while lining up on the runway and go for it.

Good grief—the Six is no hotrod, but it’s never been this reluctant to accelerate. You know you and your buddies have packed on a few pounds since high school, but there are only four of you in the airplane—it can’t be over gross. “Come on you slug, we’re running a little short on runway here. I can’t abort, I’ve got a clearance void time and it’ll be a pain in the whatsis to sort that out if I don’t pick it up.”

The airspeed finally tickles the bottom of the white arc, so you pull on another notch of flaps and the Six comes off the ground. Now you can accelerate in ground effect, although the nose sure seems high. There goes the end of the runway. You’re still in ground effect—and suddenly those trees that seemed so far away are here and now.

It’s About Time

Accidents have happened as pilots have picked up their clearance and then tried to beat oncoming weather, trying to launch but had wind shear from an approaching front or roll cloud, or severe turbulence emanating from a thunderstorm, snatch them out of their initial climb. Cabin doors have popped open during the takeoff roll and goal-oriented pilots have attempted to continue the takeoff, only to find the airplane flies miserably and controlling it long enough to get it onto a runway becomes a maybe so/maybe not proposition. Worse yet, pilots have thundered down the runway while attempting to wrestle a door closed, then lost control and wrecked the airplane.

Intellectually, we know we can extend an instrument clearance, or even file another flight plan if we can’t blast off when the departure window opens for us, yet it’s sometimes difficult to internalize that message.

At a towered airport, after being number six in line for departure and sitting through everyone ahead of you “awaiting IFR release,” it’s not unusual to have omitted something from the pre-takeoff checklist, such as closing and latching doors or windows on a hot day, or forgetting to go full-rich on the mixture from its I-don’t-want-to-foul-the-plugs position while idling. Then, suddenly, you get the IFR release and a clearance for immediate takeoff because there’s a Citation on a three-mile final. About the time you are accelerating onto the runway you realize all is not well and there’s the overwhelming temptation to fix it on the fly. What else did you forget?


There are some simple strategies for ensuring all goes well on takeoff when planning to pick up an IFR clearance. First, keep in mind that if all is not well, it’s far better to deal with it on the ground than in the air—you can always get another IFR clearance or extend the one you have. Looking stupid on the NTSB accident report because you felt hurried is not the way you want to be remembered.

At a non-towered field, wait until your run-up is complete and you’re in a position to easily take off within five minutes or so before you call for your instrument clearance and release. That gives you time to make sure you’ve got everything done and that you can use all of the runway before you move the throttle from quiet to noisy.

If ATC gives you a clearance void time that is going to rush you too much, say so. Ask for a later one. Almost invariably I’ve been able to push it back when I’ve made the request. If you can’t, it’s usually because an inbound is conflicting. If the weather is decent and you can stay VFR, tell ATC you’ll pick up your clearance in the air. Then, take off when you’re sure everything’s ready, call ATC and you’ll get your clearance when traffic separation and altitude allows. If conditions are IFR, be a little patient and let the inbound land—you might even make the phone call to the controlling authority when you see the inbound on final.

At a towered airport, don’t call ready for takeoff unless you really are. If you’ve been in line waiting for takeoff clearance, run the final pre-takeoff checklist when you’re number two in the sequence so you have absolutely everything ready to go when you become number one. Enlist informed passengers to help confirm that doors and windows are shut.

Once you start the takeoff, it’s up to the airplane to convince you it’s okay to continue, regardless of whether you’re working against a clearance void time or taking off for some pattern work on a clear day. As you go through the abort analysis checklist below, remember you are spring-loaded to the abort position. If the airplane doesn’t demonstrate it’s fit and performing, you abort the takeoff—no second thoughts or hesitation. When you abort, don’t mess around. Abort. There are no half measures.


If in doubt, abort rather than go. The force of impact is a squared function—it is far, far better to hit obstructions off the end of the runway at 20 knots than while staggering along in ground effect at 60. If everyone is wearing shoulder harnesses, the chances of walking away from the 20-knot impact are excellent—they’re much worse at 60 knots.

If you do go off the runway and are going to hit something, continue trying to make the airplane go where you want it to go until it comes to a complete stop—keep aiming at the soft and cheap stuff. If possible, keep the airplane from yawing—it will absorb much more energy and protect its occupants when hitting something head-on instead of sideways.

Once you’ve stopped, sort things out. If you’re on the runway, taxi off and follow the recommendations in the next few paragraphs. If you’ve run off the end without damaging anything, shut down and take some time to assess what you should do next—simply attempting to taxi back to the runway may turn an unharmed airplane into a damaged one. If you’ve hit something, shut down and attend to your passengers, getting them out and away from the airplane (if they can be safely moved).

Assuming you made a routine abort, turn off the runway. If you’re at a towered airport, it’s just a matter of telling ATC you’ve aborted and what you want to do next, based on your objective analysis of the situation. You may want to taxi to the ramp for maintenance or deal with a suddenly ill passenger. You may want to taxi back for another takeoff because once clear of the runway you closed and latched the door or set the flaps you forgot. Tell ATC what you want done with your IFR flight plan: you’ll pick up a new release at the end of the runway, extend it 30 minutes as you sort out what you anticipate to be a minor problem or cancel it and re-file later.

At a non-towered airport, once you get clear of the runway and know what you’re going to do, use your cellphone to call ATC and advise your intentions. Don’t try to hurry back to the end of the runway and launch with the existing void time—you’ll just be attaching another link to the accident chain.


When something goes wrong immediately after takeoff—gear hangs, fuel pump fails, you name it—it’s time to land. If you’ve already picked up your IFR clearance, you’re actually a little better off than if you’re VFR. Tell ATC you’ve got a problem and what you want to do.

If the gear will come back down and lock, you just get sequenced into the appropriate arrival, visual or instrument approach back into the departure airport or your departure alternate—your call—just tell ATC where you want to go. If it’s anything worse, declare an emergency and get priority handling to the airport and runway of your choice—ATC gets everyone else out of the way.

If you’re climbing out VFR from a non-towered airport and haven’t picked up your instrument clearance or haven’t established contact with ATC, turn around, use CTAF to let other traffic know you are returning with a problem and land the airplane. You can call ATC later, on the phone. In that situation, ATC may not be able to do a lot for you while you’re in the air and the distraction of trying to establish contact may not be what you need.


There’s seems to be an increased sense of a need to succeed when making a takeoff on an IFR flight plan. It may manifest itself as cutting corners while trying to takeoff within a clearance void time or not paying attention to the airplane telling you that it’s not in condition to make the takeoff under the conditions.

If the airplane doesn’t prove to you that you should be continuing a takeoff, it’s time to abort—aggressively. At that point, all thoughts of the fact that you are on an IFR flight plan or will blow through your clearance void time should become secondary as you focus on getting the airplane stopped in the available runway. Only after that is done need you worry about getting another clearance.

Killer Factors On Instrument Takeoffs

An instrument takeoff is just like any other takeoff, except when it isn’t. The self-imposed pressures of a clearance void time, a distant appointment or passenger expectations can mean we’ll ignore or minimize the importance of ensuring the airplane is ready, even when we need to the most. Some common problems are discussed below.

Gross Weight

It’s a choice made by the pilot. When a 10-percent increase in weight increases the distance over an obstacle by 21 percent, it’s worth a pilot’s undivided attention and respect.

Intersection Takeoffs

Do you really want to make one? It’s interesting how often an accident report mentions the pilot initiated takeoff from a runway intersection. Are there other shortcuts the pilot is willing to take that cut into the margins on clearing that obstacle or ensuring the airplane is ready?

Predicted Performance

Does the manual say the airplane will clear an obstacle in the available distance? If not, attempting to take off is stupid and may be criminal. Over some years of involvement in aviation lawsuits regarding takeoff performance, I’ve found that a properly maintained airplane will usually meet book takeoff performance, but it truly has to be properly maintained. The engine has to be developing full rated power; the prop has to be in good shape, the tires properly inflated and the brakes not dragging. A lot of people recommend a margin above the book performance numbers for deciding on whether to make a takeoff—I think they’re right.

Dragging Brake(s)/Low Tires

Keep track of how much power it takes to taxi at your normal speed on flat, dry pavement in light winds. For most airplanes, it will run on the order of 1000 rpm. If the power needed goes up by about 200 rpm, find out why before making a takeoff.

Proper Acceleration On Takeoff

Here’s the big one. There is a good decision parameter on continuing a takeoff: The airplane will break ground in the available runway length if, by the halfway point of the runway, it has reached 71-percent of the published speed at which the nose is to be raised on takeoff. If the manual says to raise the nose at 60 KIAS, then it’s necessary to have at least 42 KIAS at midfield. If not, it should be an automatic abort. This go/no-go parameter does not guarantee obstacle clearance; it just gives information regarding getting off the ground in the available runway.


Locked or jammed controls or badly mis-set trim have caused some nasty accidents. The parameter is that when you go to raise the nose on takeoff, if the control wheel does not physically move aft when normal or slightly more than normal pressure is applied—and the nose does not start coming up—abort the takeoff. You may run off the end of the runway, but that is almost invariably better than trying to continue at high power.

Abort-Analysis Checklist

It’s up to the airplane to demonstrate to us it’s capable of performing on takeoff. And it’s up to us to ensure it’s doing what it’s supposed to do and, if not, to abort the takeoff and live to fly another time. At most of the airports from which we fly, even a runway overrun, like the one pictured above, results in no or minimal damage.

Remember: Aborting a takeoff isn’t a failure on the part of the pilot; it’s a pilot showing the right stuff by recognizing the wrong stuff and taking action to keep people alive.

Lineup Check

Are trim tabs, flaps and fuel selector(s) properly positioned? If not, fix or abort. If yes, continue.

Takeoff Roll

At full throttle, are the rpm and/or manifold pressure and fuel flow where they should be for the elevation and temperature? If not, abort. If yes, continue.


It should be off the peg and moving smoothly within 5 to 10 seconds of adding full power. If not, abort. If yes, continue.

Runway Midpoint

Has the airplane reached at least 71 percent of the published liftoff/rotation speed? If no, abort. If yes, continue.


At the published speed, does moving the pitch control aft raise the nose? If not, abort. If yes, continue, and enjoy the flight.

Rick Durden holds an ATP with Douglas DC-3 and Cessna Citation type ratings and CFII, and is the author of The Thinking Pilot’s Flight Manual or, How to Survive Flying Little Airplanes and Have a Ball Doing It, Vols. 1 & 2.

This article originally appeared in the August 2015 issue of Aviation Safety magazine.

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