Good Question

[Guest B1900 Mech]

9. You are flying at 11,000 feet at 280 knots. ATC clears you to 8,000 and requests that you keep your speed up. According to FAR 91.117(a), you must:1.Comply with ATC's request.2.Slow to below 250 knots.3.Slow to below 200 knots.

[Guest Stratus_Fractus]

I'd say two. (But I may be wrong)

[Guest]

ATC cannot authorize you to exceed 250 knots below 10,000ft. Only the FAA Administrator can. 91.117(a)ATC can authorize you to exceed 200 knots while operating within Class C or D airspace but not Class B. 91.117(:( ATC requirement to

[Guest Stratus_Fractus]

Exactly. ;-)

[Guest jrewing]

14 CFR 91.117(d)If the minimum safe airspeed for any particular operation is greater than the maximum speed prescribed in this section, the aircraft may be operated at that minimum speed.I don't know of an aircraft that might fall under this provision. Perhaps the space shuttle during reentry? ;-)John

[Guest]

in atlanta they rountinely ask people to go beyond 250 (of course it is later in the evening), while in B-airspace.

[Guest]

I think the Concorde falls under that exemption.But I may be wrong.CF-AOAKyle

[Guest AndrewW]

I think the Concorde falls under that exemption.Correct. In the U.S (NY) you slow from 350KIAS to 250Kts when within 12nm of land. On Approach into London Heathrow, it's around 10Nm to Ockham (OCK). It takes about 7 miles to slow from 350Kias to 250Kts in Concorde. Hope this helps. Andrew

[Guest]

John is correct, well the regulation he cites is correct. Of course the original question is a tad vague on airspace/aircraft type etc but assuming (deadly thing to do on AVSIM) we are talking "normal" here.Some 747-400 weights on departure will require, based on the approved FAA manual to maintain a speed higher than the 250 knt speed limit. HOWEVER, that is on a departure and the speed is coordinated between the ATC and the crew (Generally on a notation on the flightplan and also a verbal call to tower prior to departure and also to the departure controller. "Tower, Northwest 5 gonna need 280 knots in climb-out" generally is the request. ATC will approve it and is well aware of the parameters of the aircraft.Sometimes it is much more "political" to get the best rate of climb you can at a reasonable, approved speed than loiter at 300 fpm at 250 IAS and spreading noise all over the neighboring towns......this gets into the mucky world of sound "footprints" etc. The "Approval of the FAA Administer" does not mean they blow in a call to FAA HQ (or her/his house at 3:30AM) in DC each time this occures. This is an administrative matter done when the FAA "approves" an aircraft manual or air carrier ops spec. Technically, any OPS specification FAA sign off on an aircraft manual will have a stamp with the clause "....for the Administrator". The original question here is an arrival though. It is highly doubtful that a "heavy" would be needing that fast an IAS due to weight on an arrival (Max Landing Weight limit) unless he was having a "problem".In day to day ops I'd be doing 280 to ten, slow (up to 12 mile "coasting level in a 757 without speedbrakes (ruins your efficiencies), then drop to eight. Again the ORIGINAL question mentions nothing of a lower altitude crossing restriction etc that gums up the speed-planning/rate of decent. Generally anytime a controller says "keep your speed-up" on the arrival sequence he is refering to the best speed forward you can maintain to the marker and still be able to configure for a safe approach and landing. Generally about 180 knts to the marker then dumping everything out (kinda freaks the passengers). A controller will say that a lot to something like a King Air or smaller plane as a "tweak" to make'em aware that something faster is coming up behind you. More often than not ATC will assign a speed so they can have one-more-component "controlled" on his PVD.Then there is the military........ OK, I am going back to sleep on a lumpy hotel mattress....Tim757