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slim75
10th Apr 2011, 09:28
Hello, can anyone please tell me where the FAA rule of maintaining 250knts below 10,000 feet came from and what it's based on?? i've looked through the FAA's most current order (JO 7110.65T) dated Aug'10 and can't find it there. Is this speed restriction in use under ICAO??

Also, the order indicates that wake turbulence criteria for operating behind a 757 is now 5miles and 2 min seperation for large aircraft.... but does that pertain to those -57s with blended winglets aswell?

thank you in advance...

slim

Capn Bloggs
10th Apr 2011, 14:28
250 below 10k: try this Origin of the 250 knots below 10,000 ft rule [Archive] - PPRuNe Forums (http://www.pprune.org/archive/index.php/t-134138.html)

In ICAO airspace? Yes and no, depending on the class. A, B, C: no speed restriction. D, E, G: max 250 below 10k. Don't know about F, but I assume it's also 250/10k.

That said, speed restrictions are sometimes imposed regardless of the airspace class. I think the Yanks are 250/10k regardless.

aterpster
10th Apr 2011, 17:51
slim75:

Hello, can anyone please tell me where the FAA rule of maintaining 250knts below 10,000 feet came from and what it's based on??

It came from two mid-air collisions. When jet transports where introduced in the U.S., there was no speed limit except within the "airport traffic area." (Generally within 5 miles of the airport below 2,000 or 3,000 feet at the time.)

December, 1960 a UAL DC-8 blows a holding fix and plows into a TWA Connie over New York in IMC. The DC-8 was at either 6,000 or 5,000 going at roughly barber pole. This resulted in 250 KIAS below 10,000 within 30 miles of the destination airport.

March, 1967, a TWA DC-9-10 plows into a Beech Baron at 8,000 going at high speed from KPIT to KDAY. The DC-9 was going at high speed because he was more than 30 miles from destination. This accident resulted in a max of 250 KIAS below 10,000 in domestic airspace.


Is this speed restriction in use under ICAO??

So far as I know it's up to the member state. JAA may have a more definitive rule.

sevenstrokeroll
10th Apr 2011, 20:54
for awhile I flew between Canada and the US...you can go faster in Canada below 10,000...but there are some exceptions...

aterpsters story tells it all for the why of it.

Capn Bloggs
11th Apr 2011, 07:32
ICAO Airspace Classes and speed limits:

Page 58 of this document (still correct as far as I can tell):

ICAO ANNEX 11 - AIR TRAFFIC SERVICES (http://www.scribd.com/doc/51230318/ICAO-ANNEX-11-AIR-TRAFFIC-SERVICES)

TAAMGuy
14th Apr 2011, 16:07
Canadian controllers have recently (Nov 2010, I believe) been prohibited from removing the 250kt restriction below 10T for the departures. Controllers could never unrestrict arrivals. The impetus for this speed restriction came at a time when there was more of a variation in performance between types operating in a TMA. Nowadays, with current surveillance technology, and a more consistent mix of performers in and out of the major airports, the issue is less significant. However, another consideration has been bird strikes; not that I personally think it valid. I assume the speed restriction was an attempt to mitigate the severity of damage resulting from a strike. With the fans adorning newer generation aircraft, I'm not sure how much weight should be given to this consideration.

I know that there is a fairly strong lobby in Canada to have this restriction removed, again, at least for departures. It gives controllers another few tools in the old tool bag to better tactically deal with traffic. Whether or not Transport Canada will write out of our regs remains to be seen. At least the old "unless otherwise authorized by ATC" should be brought back into effect. IMHO.

slim75
15th Apr 2011, 00:42
thank you all for your insights... very helpful.

-slim