mjsmigel
Posts: 57
Joined: Thu Oct 31, 2002 4:57 am

Extreme Speeds On Approach/takeoff

Mon Nov 11, 2002 4:09 pm

Is it common for very high speeds to be used for takeoff/landing, simply because an airplane has a low gross weight and the runway is much longer than required?

I ask this because back in the late 1980s I reviewed some footage of aircraft taking off from DFW. I did some photogrammetry. Knowing exactly how many frames per second were in a "frame advance" on the VCR, and the fuselage length of that particular model, I used the speed = distance / time formula. I found some AA/DL MD-80 aircraft had reached 180-200 kt (error 10%) before they lifted off.

I assumed something was wrong in my computations until years later, when I discovered all this:

-- Continental DC-9 at IAH in 1996, too hot (200+ kt) on the final approach and rolled off the runway.
http://www.ntsb.gov/NTSB/brief.asp?ev_id=20001208X05238&key=1

-- TACA 767 that had a similar incident in Guatemala in 1993.

-- American Airlines 727 at CVG in 1965 was 300+ kt on the base leg
http://aviation-safety.net/database/1965/651108-3.htm

-- Depending on the aircrew, Key Airlines 727-100's I flew on from Tonopah Test Range into Nellis AFB 1989-90 sometimes flew highly unstabilized final approaches... I was on three flights where the pilot did an extremely short final, turning from base to final over the approach lights about 200 ft AGL.

It might be safe to assume that hot approaches/takeoffs are more common than we think.

On the other hand, the times that I used my GPS during takeoff/landing on Delta and Continental 727/737 flights in recent years, all speeds looked perfectly reasonable to me (110-140 kt).

I'm not trying to start a fire here or anything... this topic has always piqued my curiosity.

Pics of aircraft involved in hot approaches shown below for enjoyment...

MJ


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Photo © Bryan Correira




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Photo © Frank Schaefer






 
Guest

RE: Extreme Speeds On Approach/takeoff

Mon Nov 11, 2002 4:50 pm

Dear Mjsmigel -
xxx
I dont know if the 747 is the worst aircraft (being large and heavy) but here are the speeds applicable for a 747-200/300...
xxx
Takeoff maximum weight -
V2 speed (50 feet above runway) is 190 kts...
After flaps retraction we need V2+100 for maneuvers = 290 kts when climbing.
xxx
Landing maximum weight -
Vref speed 154 kts... we establish that speed no later than 500 feet AGL...
Add some 10 kts, maybe 15 knots for wind... rarely over 160 for landing.
xxx
Realize also that planes are not at maximum weights, meaning = slower...
Cheers -
(s) Skipper  Smile
 
Skystar
Posts: 1339
Joined: Thu Jan 13, 2000 3:58 pm

RE: Extreme Speeds On Approach/takeoff

Mon Nov 11, 2002 5:11 pm

The MD-11 also has some pretty high Vspeeds too, IIRC they might even be higher than the 747 at times.
 
Bellerophon
Posts: 516
Joined: Thu May 09, 2002 10:12 am

RE: Extreme Speeds On Approach/takeoff

Mon Nov 11, 2002 11:17 pm

Mjsmigel

Remember that what you have calculated from your film (and also what the readout on your GPS showed) is the aircraft groundspeed (GS). What the pilot was using was indicated airspeed (IAS), and you would need to know what the wind at take-off was to deduce the IAS.

It is possible there was a tail wind component on the take-offs you looked at, which would mean the GS was higher than the IAS.

Most airline operators instruct their pilots fly the scheduled speeds, and most lay down a point by which an approach must be stabilised. In the event of an incident, the Flight Data Recorder will show exactly how the aircraft was being flown, and any deliberate breach of company procedures it reveals is unlikely to be treated with much sympathy.

If you have calculated your take-off and approach speeds correctly, in accordance with the Aircraft Flight Manual, using the prevailing atmospheric conditions, then there is nothing to be gained by arbitrarily increasing those speeds. In my experience, the vast majority of airline pilots fly by the numbers.

For my aircraft type, at maximum weights, typical speeds are:

Rotate..................193 kts
V2........................214 kts
Initial Climb Out.....250 kts
Approach..............192 kts.........down to 800R
Landing................169 kts...stabilised by 500R

Regards

Bellerophon







 
ThirtyEcho
Posts: 1409
Joined: Tue Jan 01, 2002 1:21 am

RE: Extreme Speeds On Approach/takeoff

Tue Nov 12, 2002 4:59 am

Remember that taking off into the wind means that the GS will be lower than the IAS; all that your system of speed estimation produces is a GS reading, even if it is accurate. If an aircraft rotates at 150KIAS, but is flying directly into a 20KT headwind, its groundspeed is only 130KTS.
 
POSITIVE RATE
Posts: 2121
Joined: Sun Sep 16, 2001 11:31 am

RE: Extreme Speeds On Approach/takeoff

Tue Nov 12, 2002 1:53 pm

To add to what ThirtyEcho said- the temperature may have been quite high also which would have meant that the TAS and therefore the GS would have been quite high by the time you reach VR IAS. High temps=High TAS for the same IAS
 
XFSUgimpLB41X
Posts: 3960
Joined: Fri Aug 25, 2000 1:18 am

RE: Extreme Speeds On Approach/takeoff

Tue Nov 12, 2002 2:07 pm

What kind of bird do you fly, Bellerophon? Those are some high t/o speeds. I remember Vr at max t/o was in the 160's in the DC-10.... and thats right around 600,000 pounds....
Chicks dig winglets.
 
learpilot
Posts: 783
Joined: Thu May 10, 2001 11:07 am

RE: Extreme Speeds On Approach/takeoff

Wed Nov 13, 2002 11:39 am

I'm no expert, but I'm guessing we have a Concorde driver among us!
Heed our warnings or your future will be underpant free!
 
OPNLguy
Posts: 11191
Joined: Tue Jun 15, 1999 11:29 am

RE: Extreme Speeds On Approach/takeoff

Wed Nov 13, 2002 11:53 am

>>>-- Continental DC-9 at IAH in 1996, too hot (200+ kt) on the final approach and rolled off the runway.

Well, yes, they were indeed fast, but it wasn't a "normal" approach by any stretch of the imagination. If you'll look at the NTSB stuff you linked, you'll note that they didn't have hydraulic pressure available to actually extend the landing gear and flaps because of a human error. That error initiated the accident chain, and the excessive speed was a consequence of that error, and not the error itself...
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.

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