# How or when can the 250 KIAS speed limit below 10,000ft be exceeded?

This arose out of a comments discussion in this question.

The only airspace I really know is the UK. Here, a controller may issue a clearance to exceed the 250kt limit below 10,000ft for reasons other than minimum safe flying speed, e.g. to expedite a transition for spacing.

Is this common, e.g. in the US? I know it's open ended but I'm interested in whether this is just some "local" thing.

• The German BAFVD (the controller's bible) lists that the speed restrictions can be lifted for technical reasons (aircraft limitations) and for security reasons. I queried two of my colleagues working TMA airspaces and they said that it depends on the controller when they lift the limitations. Some will keep aircraft in the protected class C and some will allow higher speeds in class E, when weather conditions do not allow VFR operations anyway. The BAFVD is not public though, so I'll leave this as a comment for you, no real answer. :/ – SentryRaven Jan 22 '15 at 10:25
• The notion of a speed limit for airplanes raises the humorous image of a cop sitting behind a cloud with a radar detector waiting for a plane to go by... ;-) – Michael Jan 22 '15 at 19:05
• @Michael as long as we're being silly; why bother with a cloud: snopes.com/horrors/techno/radar.asp – Dan Is Fiddling By Firelight Jan 22 '15 at 23:44
• @DanNeely Coincidentally a colleague sent me a copy of that text yesterday (not snopes) with the disclaimer, "probably fake". I immediately shot back "It has to be, Sidewinders are air-to-air missiles, not air-to-ground". We then proceeded to take apart the other flaws before finding the snopes copy. – Michael Jan 22 '15 at 23:50
• @Michael Not only is the Sidewinder an air-to-air but it's a heat seeker. The missile that would go after a hostile radar is a HARM. – Loren Pechtel Jan 23 '15 at 0:54

Not a local thing at all!

In Australia, it is extremely common to hear, especially for aircraft on departure. Listening to LiveATC, particularly Sydney International Approach/Departure (YSSY) you will quite often hear ATC give an aircraft permission to exceed 250KIAS below 10,000ft.

Qantas 123: Approach, QFA123, with you passing 2,300, climbing 5,000..

Sydney Approach: QFA123, Identified, Climb FL240, cancel speed restrictions below 10,000..

There are a number of reasons this is used. The first, I have already hinted to in the example radio call above.

Departures: It is extremely common to hear ATC cancel speed restrictions on departing aircraft. This gives better separation for aircraft departing in the same direction. For example, one of the busiest sectors in the world is Sydney - Melbourne Australia. The common SID's out of Sydney for Melbourne are the DEENA4 WOL transition and the WOL1 Departure, depending on operational runway. As a large amount of aircraft use these departures, the further the lead aircraft can get on the SID prior to the trailing aircraft becoming airborne, the better.

Arrivals: Again, using Sydney, they receive a large amount of Regional Turbo-Prop traffic (Dash 8-Q300/Q400, Saab 340B, BE350). You will commonly hear Approach cancel speed restrictions on these aircraft on decent so they can give them more space on the approach. They land reasonably slower than a B747/A380, so the more room, the better.

Another reason is simple. These guys are operating commercial operations, hence faster is better, especially on descent. So if there is no or low traffic in the TMA, ATC will commonly release the speed restriction on aircraft to accommodate the company operations.

• I'd forgotten about the SIDs. In the UK, it is common to hear "no speed" meaning no restriction. If it happens in Aus, then safe to assume it's widespread. Thank you! – Simon Jan 22 '15 at 10:20
• @rbp He is not directly stating it needs to be US, he is using eg. US as a way of saying not in the UK.. – James Ham Jan 22 '15 at 12:54

In the US, the 250 kt speed limit is codified in 14 CFR 91.117

§91.117 Aircraft speed.

(a) Unless otherwise authorized by the Administrator, no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 m.p.h.).

(b) Unless otherwise authorized or required by ATC, no person may operate an aircraft at or below 2,500 feet above the surface within 4 nautical miles of the primary airport of a Class C or Class D airspace area at an indicated airspeed of more than 200 knots (230 mph.). This paragraph (b) does not apply to any operations within a Class B airspace area. Such operations shall comply with paragraph (a) of this section.

(c) No person may operate an aircraft in the airspace underlying a Class B airspace area designated for an airport or in a VFR corridor designated through such a Class B airspace area, at an indicated airspeed of more than 200 knots (230 mph).

(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.

Note in section (a) that only the administrator may authorize operations below 10,000 feet MSL at speeds above 250 KIAS. The only exception to this is part (d) which applies to aircraft that cannot safely operate below this speed. As far as I know this only applies to specific heavy airplanes. ATC does not have the authority to issue instructions contrary to regulation.

Historically the FAA has experimented with the ability of controllers to cancel the 250 kt speed limit within certain class B airspace, notably in the Houston, TX class B. That program was discontinued and currently no controller may grant you an exception to the regulation.

Note that the 200 kt speed limit in class C and D surface areas and any speed restriction published on a chart (departure and arrival procedures) can be cancelled by ATC.

• The military also can fly at 300kts below 10k, and often, even 350. It can be very challenging to both descend and slow down a division of aircraft, so we often fly faster for safety. – Rhino Driver Jul 22 '15 at 5:54

In the US, speed restrictions are frequently cancelled, either to ensure or to increase separation between aircraft, as per ATC Handbook 4/3/14 JO 7110.65V, Section 5-7. Speed Adjustment:

5−7−1. APPLICATION Keep speed adjustments to the minimum necessary to achieve or maintain required or desired spacing.

• Published restrictions on arrivals and departures may be cancelled, but the 250 kt limit below 10,000 MSL may not be. – casey Jan 22 '15 at 21:18
• @casey So what I'm hearing is that in large areas of the world (so far, I know UK and Aus), it can be cancelled, in the US not. Is that a fair summary so far? – Simon Jan 22 '15 at 21:37
• @casey retracted. it says Administrator, not ATC – rbp Jan 22 '15 at 22:12
• FAR §1.1 General definitions. Administrator means the Federal Aviation Administrator or any person to whom he has delegated his authority in the matter concerned. – JScarry Dec 28 '16 at 18:49
• notably: "in the matter concerned" – rbp Jan 20 '17 at 15:46