BOEING 737-800
STANDARD TAKEOFF
NORMAL SPEED
FLAP ONE
GOOD PILOT

(If you are a pilot, work in the aviation industry, or Googled the answer, feel free to vote, but don’t ruin it for others.)

Question:
At the point where the aircraft attains maximum rotation (@Vr), how far normally is the tail from the surface of the runway?

Choices:
The thickness of a penny.
About one foot.
Exactly one meter (+/- a couple mm).
Just under the height of a 6 foot man.
Some 2 stories (6 meters or about 20 feet).

 

No reason for an ALL CAPS subject line

^Sorry, Para. Fixed.

Far enough so that the paint stays on the bird.

I don't know but I have been on a 727 when the tail scraped on takeoff.

quote:

Originally posted by 220-9er:
I don't know but I have been on a 727 when the tail scraped on takeoff.

I wonder how often tailstrikes really occur. They rarely cause major damage, but I believe if it's on takeoff the plane is required to return back to the airport for inspection.

And sometimes they do cause something major. A tailstrike that happened 7 years previous led to a faulty repair on a rear bulkhead that blew out in flight and caused the crash of JAL 123.

Kkina, you are assuming that the crew notices. I myself have never had one, but I know one or two who have (neither critical) and neither one of them had any idea. The only indication was missing paint on the plane, or on the tail skid plate.

Also, FWIW, most of the tail strikes I have heard of have been due to over-flaring on the landing rather than over-rotation on takeoff. I'm sure there are those just ready to whip out a plethora of statistics...but I'm not that guy.

"Did you feel that?"

"Feel what? All I want to feel is my bed."

The original question referred to take-off. Otto's post suggests that tail strikes might be more common on landing.

kkina's "Did you feel that?" post, just above with the photo of the TRANSAERO airplane, looks like it's landing, not taking off. Note the smoke rolling back from the tires.

quote:

Originally posted by 220-9er:
I don't know but I have been on a 727 when the tail scraped on takeoff.

I'd swear that's the noise I heard too!

quote:

kkina's "Did you feel that?" post, just above with the photo of the TRANSAERO airplane, looks like it's landing, not taking off. Note the smoke rolling back from the tires.

That's correct. The Transaero looks like a (hard) landing. Posted just for humor purposes (guess it's not so amusing if you're there).

I heard that tailstrikes are more common on T/O, but haven't seen actual statistics. That would actually be a good thing, as landings would be far more dangerous due to the downward momentum of the aircraft descending adding so much more force.

I guessed a meter but have a problem with the word “exactly” in that choice.

The one-footers have it. Normal clearance is 31 cm, or about 1 foot.

I was surprised myself. I thought it would be a huge amount, like 20 feet. If it's just a foot, no wonder tailstrikes happen sometimes.

I guess it's true that airplanes are designed to fly, not take off, land, or taxi.

Interesting article I found related to tail strikes from the Boeing web site.

https://www.boeing.com/commerc...RO_Q107_article2.pdf

If I read correctly, a 12.5 degree pitch on takeoff will cause a tail strike.
And in the case of a 747-400, one would have about 100cm clearance at 10 degrees.

OK, so I had to dig out the book just for grins.

On our 767-200 typical liftoff pitch angle at flaps 5 is 11.1 degrees with a tail strike pitch of 13.1 degrees with a typical flyaway clearance of 25 inches on the tail.

On the -300, the liftoff target pitch is 7.5 degrees with a tailstrike pitch of 9.6. Tail clearance is similar at 24 inches.

This points to an interesting gotcha when flying a fleet with different length airframes. As you can see, the tailstrike pitch on the long plane is actually LESS than the flyaway pitch on the shorter plane. This is why slow steady pitch of ~2 degrees per second is critical to give the plane time to generate lift and start lifting off before the critical angles are achieved while still on the ground.

Question for Otto: I have never been in the front office of a modern Boeing, nor in a simulator for one.

I would have assumed that a computer generated Flight Director presentation would command the correct pitch attitude for takeoff. Not true?

Depending on options that are equipped, many of the 36 series Bonanzas that I have flown have TakeOff / GoAround button on the yoke. Press this and the FD comes alive and commands the initial climb attitude for hand flying, and of course the AP can be engaged to follow the FD commands.

I would expect something more sophisticated on the equipment that you fly.

Most use 5 flaps, depending on performance limitations.

Mr. V-Tail...our Flight Manual (FM) states to rotate at Vr "without delay" (to avoid tailstrike and tire overspeed) with a rotation rate of 2.0-2.5 degrees per second up to 15 degree initial pitch. It also states to NOT rely on flight director pitch command bars as guidance to achieve this. I'm going to wager this is the common guidance in every airline's B737 FM.

As to Otto's point about there being differences for longer-bodied airframes, the B737 manual makes no distinction with respect to whether we're in a -700, -800, -900, -900ER, or MAX-9/10. It's the same takeoff procedure/technique for all variants of the B737. However, and again to Otto's point, the likelihood of a tailstrike due to improper/over-rotation would be higher on the -900ER vs. the -700 due to its fuselage length. "Generic" takeoff technique has been established so that we can rotate the exact same way throughout the B737 fleet and not cause a tailstrike.

quote:

Originally posted by V-Tail:
Question for Otto: I have never been in the front office of a modern Boeing, nor in a simulator for one.

I would have assumed that a computer generated Flight Director presentation would command the correct pitch attitude for takeoff. Not true?

Depending on options that are equipped, many of the 36 series Bonanzas that I have flown have TakeOff / GoAround button on the yoke. Press this and the FD comes alive and commands the initial climb attitude for hand flying, and of course the AP can be engaged to follow the FD commands.

I would expect something more sophisticated on the equipment that you fly.

On the 737 the Flight Director becomes active when you press the TOGA button on the thrust lever. However the FD only provides flight path guidance, it does not provide "rate" guidance. Our manual warns against trying to use the FD for rotation as the pitch rate may be too fast and induce a tail strike. I believe some aircraft/airlines have a tail strike pitch limit displayed either on the PFD or HUD depending on installation. We don't have anything like that at the LUV airline, we do have a TO pitch report you can access after takeoff that will show your actual pitch attitude on takeoff and the limit. I believe in the -800 the limit is around 11*, I've never seen anything close to that.