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14 CFR 91.117 limits aircraft to 250 knots indicated airspeed below 10,000 feet, but 91.117(d) allows aircraft to fly a higher speed if the minimum safe speed is higher. What aircraft and aircraft conditions might require an indicated airspeed higher than 250 knots?

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    $\begingroup$ If the bleed air system isn't working, the F-104 has a landing speed of 240kts since it uses a blown-flap system. It may be reasonable for a pilot to be above this speed on approach. Normally I wouldn't suggest a military aircraft, but there are privately owned F-104's. Some aircraft like the 747 get pretty squirrely when clean and heavy below those speeds, I think the A380 may be in the same boat. $\endgroup$ – Ron Beyer Jan 8 '17 at 4:09
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    $\begingroup$ The limit is 250 knots indicated air speed (KIAS). IAS is not corrected for instrument and position error nor is it corrected for winds. Thus any aircraft can exceed 250 knots ground speed as long as their air speed indicator shows less than 250 KIAS. This can easily happen with tail wind component. $\endgroup$ – Steve Kuo Jan 8 '17 at 20:20
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    $\begingroup$ @SteveKuo I wasn't confused about the type of airspeed, but I'll update the question to clarify. $\endgroup$ – ryan1618 Jan 8 '17 at 22:03
  • $\begingroup$ I'm also interested in a definitive list. $\endgroup$ – Keegan Jul 2 at 2:19
  • $\begingroup$ Possible supplemental question-- in what US airspace below 10,000' MSL would 14 CFR 91.117 generally not apply to military aircraft? Also included in the scope of the question should be in what types of airspace has the Administrator made a permanent blanket authorization to exempt military aircraft from 14 CFR 91.117. (Thinking of MOAs, restricted airspace, low-level training routes, etc.) Feel free anyone to grab it, tweak it, and ask it unless the answer is too obvious. $\endgroup$ – quiet flyer Oct 30 at 19:21
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FAA has letters of agreement with US DOD, which authorizes certain military aircraft to fly faster than 250 KIAS below 10,000 feet. A good example of this would be the Northrop T-38 Talon, described in FAA JO 7610.4 Special Military Operations:

12-10-11. AUTHORIZATIONS

T-38/T-1 airspeeds in excess of 250 KIAS below 10,000 feet MSL are authorized by competent military authority in accordance with FAA Order 7110.65 and the letter of authorization granted to DOD.

The reason for this waiver is discussed in NTSB report number FTW90FA151:

THE T-38'S SPD WAS ABOUT 330 KTS; THE SPD LIMITATION OF 250 KTS HAD BEEN WAIVED FOR T-38 ACFT, DUE TO THE ACFT'S LACK OF CONTROLLABILITY AT THE LOWER SPD.

The relevant letter from forums.jetcareers.com:

FAA Waiver

Also, from AIR FORCE INSTRUCTION 13-201:

14 CFR Part 91.117 covers aircraft speed. Recognizing that some DoD aircraft performance requirements exceed 250 knots, the FAA issued an exemption to 14 CFR Part 91.117.

The exemption has been claimed for other aircraft too- like F-15 Eagle, for example:

... climb-out occurs at 350 KCAS for an air-to-air configured jet and 330 KCAS on one with air-to-ground ordnance. ... this is significantly higher than the 14 CFR speed restriction of 250 knots below 10,000 feet. The F-15E, like most fighter aircraft, falls under the Letter of Agreement between the DoD and FAA allowing some military aircraft a waiver to that speed limit.

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    $\begingroup$ When the Concorde was in operation, its takeoff speed was about 220 knots. The delta wings on the Concorde and most other supersonic military aircraft require a high angle of attack and higher takeoff and landing speeds. Futhermore, the Concorde used afterburners on takeoff, so it was accelerating. That means that the Concorde probably also flew well over that speed limit below 10,000 ft. $\endgroup$ – Gus Jan 9 '17 at 5:11
  • $\begingroup$ Ye thirde linke breaketh. $\endgroup$ – Sean Nov 3 at 2:27
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A 747 taking off at or near max gross weight will have a flaps up, minimum safe airspeed and climbout airspeed speed greater than 250 knots. In such cases you didn't notify ATC as they expected it.

I tried to find what the exact numbers would be at 840,000 lbs, but I seem to have thrown out that manual. I did, however, find a reference for a 747-200 with JT9D-7Q engines that gives the flaps up holding speed at 800,000 lbs as 259 kts at 5,000 feet.

Also, I do remember being on an arrival once, with the weight low enough that we could safely maintain well below 250, but that when we saw we were icing badly, we speeded up to somewhere around 300 to get the ram air temp above freezing. In that case we notified ATC that we were doing so.

Also, ATC occasionally requests max speed. For example, on Hajj flights into and out of Jakarta Halim airport in the late 1990s it was common practice for controllers to put you down low to get you under the traffic into Cengkareng airport. They would then often request max speed.

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    $\begingroup$ That's the V2+100 right? $\endgroup$ – ymb1 Feb 1 '17 at 1:29
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    $\begingroup$ @ymb1 Correct, but there is one small caveat in that while most 747 carriers chose to go up through the flap settings from takeoff to a clean wing in 20 knot increments because that made it easy for the pilots to set the bugs, there was at least one carrier, the first one I flew for, that insisted the exact speeds be used. A plastic placard plastic placard grease-pencilled by the f.e. and checked by both pilots for the takeoff weight that gave the exact speed for each flap setting was put on the thrust lever console. Thus V2+ in that system was a few knots different for each flap setting. $\endgroup$ – Terry Feb 1 '17 at 7:28
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777-200 stall speed at max t.o. weight is 192 kts. 1.3 buffer brings that to 252 kts.

777-300 stall speed at max t.o. weight is 207 kts. 1.3 buffer brings that to 269 kts.

Because of the higher stall speeds, especially for the 777-300, ATC knows we'll exceed 250 kts on departure and frequently acknowledges it before we mention it. On arrival, at lighter weights, it's not an issue. On the 777-300 you don't have to have Flaps 1 out until approx 220 kts. at max landing weight. On the 777-200 it's slightly lower (approx. 215 kts). So the reduction in weight from max T.O. weight to max landing weight reduces the minimum clean speed by 35 kts (777-200) and 50 kts (777-300).

Most fighters, in normal ops with a clean wing, won't be close to stalling at 250 kts. But they can pull more G's, thereby having more maneuverability, if they're flying faster.

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    $\begingroup$ Nice info, and welcome to Av.SE! Would it be correct to assume that the 192 and 207 knot speeds are in a clean configuration? $\endgroup$ – Ralph J Oct 30 at 13:58
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A number of military aircraft - one that I can cite off the top of my head is the T-38 - have speed restriction waivers from the FAA during operations for safety. The T-38, for example, flies the traffic pattern at 270 KIAS in order to provide sufficient maneuvering capability without exceeding the AoA limitations of the aircraft and stalling it. The F-104 probably has similar limitations in performance. The SR-71 rotated at 230 KIAS and the pilot had to immediately retract the gear after liftoff to prevent structural damage from exceeding Vle of 300 KIAS.

As for commercial and civil aircraft, the speed restriction of 250 KIAS does not present much of an obstacle or impediment to safe operation, albeit it’s a little slow for jets.

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In the EA-6B we had a waiver to climb out at 300KIAS.

Coming home we were lighter and could easily make 250, but we were waivered to 300 if we were in formation to have extra margin for the wingman.

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  • $\begingroup$ At Rota or Atsugi? $\endgroup$ – Mike Brass Sep 26 '18 at 3:56
  • $\begingroup$ I was at Whidbey $\endgroup$ – Michael Hall Sep 28 '18 at 15:46
  • $\begingroup$ Why would you have to fly faster with a wingman? $\endgroup$ – Sean Nov 3 at 2:26
  • $\begingroup$ Better responsiveness from engines and flight controls. The plane gets a little mushy with flaps up between 200 & 250. $\endgroup$ – Michael Hall Nov 3 at 5:39

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