'No speed'

[FlyingOfficerKite]

If you ask a pilot why it is normal to reduce to 250kts below FL100 s/he will no doubt respond that it is to assist ATC with the management of traffic and, coupled with windshield heat, to help reduce the effect of a bird strike.

On departure when given the option by air traffic of 'no speed' pilots smile, think of the possible saving in time, and happily select VNAV speed.

What about the possibility of a bird strike?

This never seems to be considered yet is potentially just as likely as on the descent.

Is this a case of doing what we are trained and taught, rather than what would appear to be common sense?

KR

FOK

[hetfield]

In our company SOP in that case was 280 kt, but only on one particular heavy type:ugh:

[Meikleour]

Some large types like the B747 have clean speeds well in excess of 250kts. that is why they are usually happy to accelerate rather than have flaps extended up to 10,000ft.
Has been this way for well nigh 45 years. I have never seen any statistics to prove an increased risk level although I agree with you that there is an inconsistency here.

[tocamak]

My company sop is that if you are instructed to maintain a speed above 250k below Fl100 then you may do so but otherwise the limit applies i.e. "no speed" means there is no speed limit from atc but there is from the company

[ChristiaanJ]

FOK,
Dumb question from an ancient...

During a typical departure, how long would you expect to be "stooging" around below FL100 at more than 250 kts? More than about a minute or two?

Unlike an arrival, where you might well be required to "hang around" below FL100 in a hold for far more than a few minutes.

My thought being, that there would be an order of magnitude difference between time 'at risk' (or distance covered 'at risk') between a departure and an arrival.

CJ

[LeadSled]

FO Kite,
Certification takes care of bird strike, but in the GODs, I was always amused that the Imperial Standards Bird only flew to 8,000 ft, but the FAA Bald Eagle flew to 10,000 --- which hardly covers Condors over the Andes, where birdstrikes have been recorded at 28,000. I personally have had a bird strike --- at night --- at 17,000 over Bangkok ---- doing about 340kt at the time, hell of a bang, but no damage to the aircraft.

An aircraft AFM will detail any operational limits to ensure bird strike protection, but in more recent times, many aircraft (eg: B747) do not have any birdstrike limitation speeds.

Re. 250 kt/10,000' speed limits, some are statutory (eg:US) and ATC cannot give "dispensations", it is up to the PIC to determine that a minimum safe speed is greater than 250kt. From memory, FAR 91.117.

In some countries (eg: Australia) it is a bit more complicated, it is a statutory limit in D, E and G airspace, but up to ATC in C.

Tootle pip!!

[Denti]

Company limit of less than 300kts below FL100 and less than 250 below 5000ft/FL50 (applicable to all fleets, be it boeing or airbus). Those are hard limits and may not be busted in any case, be it departure or arrival. Within those limits we may help ATC with higher than 250kts, however if given "maintain highspeed" or "free speed" we have to reduce to 250, only when a specific speed is requested by ATC we may fly that if higher than 5000ft.

I'm quite happy with that, but it means i have to be a tad more conservative in my descent planning to cater for route shortening below FL100 which i cannot work around with a higher speed anymore. German airspace C has no speedlimit below FL100 which usually enabled us to fly faster than 250kts, until the company changed their inhouse limits that is.

[BOAC]

you might well be required to "hang around" below FL100 in a hold for far more than a few minutes. - I'd be interested to see your 250kt hold.......................but not to be very close.................:)

[bbrunton]

Bird strike is only part of it.

Then main reason for 250 max below 10,000 ft is because that is what I call indian territory... That is where you will find the indians.. Cherokees, along with Cessnas and all manner of slow moving aircraft..

Also the cloud clearance and visibility requirements for VFR aircraft are based on a max airspeed of 250 KIAS.. Above 10,000 ft the VFR visibility and cloud distance requirements are greater due to the higher speed.

Bird strike requirements should be met by a combination of operating limitations and procedures such as Vmo and Mmo limits.


Bill

[Pugilistic Animus]

(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.

:)

[GlueBall]

"less than 250 below 5000ft/FL50 (applicable to all fleets, be it boeing or airbus). Those are hard limits and may not be busted in any case, be it departure or arrival."

"Hard limits?" Have you ever flown B74s? . . . So if your flaps-up speed were 265, you'd rewrite the Boeing book, stay at "less than 250kts" and drag the flaps to 5000 feet? :ooh:

[Denti]

It is a hard company limit. And no, we do not fly 747s, way too inefficient for our route network, 2 engine widebodies are much better for that.

[parabellum]

I seem to remember that there was a speed limit of 250kts below 10,00' if there had been a window HEAT failure?

[The Dominican]

The origins of this regulation had nothing to do with bird strike protection because when the regulation was put in place in the early 50's who cared or was a bit concerned about bird strikes? think about it, your flying along in a tank like built DC6, DC3 or Connie and a bird strike was a non issue, but for an air traffic controller working without radar and in a congested airspace where most of the traffic wasn't going farter than 200kts. because after all, jets where a new thing in the 50's. Then the explosion of general aviation during the 60's and 70's brought the "Indian" phenomenon that somebody mentioned in an earlier post and again 250 bellow ten played a part in organizing traffic. All jets that I know of have a higher speed for bird strike protection than 250 bellow ten and all birds that pose a real danger because of their size (large migrating waterfowl for example) they all fly a lot higher than 10K. so the common sense argument of the original post is flawed. So if you are departing out of an airspace that has no speed restriction, please use your common sense and remember that the A/C taking off 45 seconds behing you is going to accelerate

[DFC]

(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 love the common inrepretation of that rule. :)

Very few people seem to notice that the above rule refers to safety and not in any way to economic or convenient operation.

Therefore, while one could argue that it may indeed be a pain in the ass and is not economic to fly a B747 at 250Kt with flap extended all the way to 10,000 it is 100% safe to do so.

If flying in Class E, F and G there is a hard limit of 250Kt below FL100 / 10,000ft because there is a posibility of encountering unknown VFR traffic and permitting the posibility of "see and avoid".

As was said previously, above FL100 the VMC minima are higher to account for the increrased speed and under ICAO, VFR flight is not normally permitted above FL195.

[ChristiaanJ]

... flying along in a tank like built DC6, DC3 or Connie and a bird strike was a non issue...,The DC3 may be pretty solidly built, but it's not birdstrike-proof.

BAC (British Aircraft Corp.) used a DC3 as a shuttle between Filton and Fairford. Very short run, so they didn't really get much higher than 2500 ft.
One day .... co-pilot bends down (to pick a pencil from the floor or suchlike).
The next moment there was an almighty bang just above his head.... a seagull had come straight through the windscreen and gone splat! against the bulkhead behind him.
He was showered with glass, blood and feathers, and the smell was atrocious, but he was not significantly injured.

CJ

[The Dominican]

I flew the "3" had several strikes with it too, so I am quite familiar with how it is built. You missed the point of my post since they didn't reduce the speed from 145 kts to 130 kts as a result of that particular incident did they? The point is that the regulation has nothing to do with bird strike protection but rather traffic management, what has to do with bird strikes is the several layers of glass and plastic which aircraft windshields are built today and all large transport aircraft's are certified to withstand a large bird impact at high speeds. the assumption of the original poster is incorrect

[Pugilistic Animus]

Never flew a 747 but I'd assume that the operators want to keep flaps down operations to a minimum out of respect for fatigue considerations....and i believe we can safely say that rule was made for her originally:)

[NG_Kaptain]

The FAA instituted the speed limit in the early 60's after a United DC8 collided with a TWA Connie over New York. The DC8 was flying real fast and overshot his fix ending up in La Guardia's airspace.

1960 New York air disaster - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/1960_New_York_air_disaster)

[Denti]

I know of a recent birdstrike on a 737 around 210 kias in 2000ft which managed to penetrate the captains window through all layers. However the captain was lucky and managed to not get injured by the shower of glass particles. So even below 250kts you might get suddenly feathered guests in the cockpit.

[MD80rookie]

I've hit a big bird over Mallorca (Europe) at FL180 / 300 KIAS. Plane OK, bird not OK.

250 below FL100 is only applied if you are flying in a TMA, at least in Sweden.

/Rookie

[galaxy flyer]

NGKaptain

Nice to know someone here has a sense of history. There were several jet vs. other mid-airs that brought about the first 250 knot rule. That accident also brought about "report navigation equipment failure to ATC" rule and the "slow down to be at holding speed 3 minutes prior to the holding fix" rule.

GF

[Bullethead]

From a post on the 'bluecoat' forum a few years ago.


BACKGROUND OF THE 250 KT RULE

The Rule
FAR 91.117(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.).

The above FAR 91.117(a) restricts all aircraft departing Class B airspace to maximum speeds of 250 kt indicated airspeed when they are below 10,000 ft altitude. This background section will describe the historical origins of this restriction, the current implementation and enforcement of the rule.

The Historical Evolution of the Rule
The current 250 kt restriction on U.S. aircraft departures in Class B airspace was a result of the historical air traffic control problem of aircraft separation in busy, terminal areas. In the earlier days of aviation, avoiding collisions by the "see and be seen" VFR rules and air traffic controller-enforced IFR rules was adequate, but as air traffic levels increased and aircraft performance improved, these safety rules were significantly augmented by airspace and speed restrictions. Beginning in 1926, the U.S. government started issuing federal regulations to enhance the safety of the "see and avoid" concept of air traffic separation (Note: an interesting account of the history of the "see and be seen" concept can be found in Appendix D of reference 1). However, federal inquiries into three mid-air collisions in the 1950s and 1960s more or less led to the imposition of the 250 kt restriction on aircraft departures in Class B airspace.

In June 30, 1956, a mid-air collision between two airline aircraft over the Grand Canyon in visual meteorological conditions occurred, resulting in significant Congressional inquiry. A result of the inquiry was the adoption of an amendment to the Civil Air Regulations on February 6, 1957.
This amendment established high-density air traffic zones around certain busy airports and aircraft in these zones were to be limited to indicated airspeeds of 160 knots. This indicated airspeed restriction was later increased to 200 knots and 250 knots as required by the higher operating speeds of the developing jet aircraft.

On December 16, 1960, two IFR-controlled airline aircraft collided near Staten Island, New York. The two aircraft were assigned the same altitude but were assigned to two different routes with safe separation. One of the contributing factors in the accident (see reference 2) was judged to be the high rate of speed of one of the aircraft that ventured outside of its cleared airspace.

One outcome of the accident over Staten Island was the publishing of Draft Release (D.R.) No. 61-9, a notice that the Federal Aviation Agency was considering the imposition of a rule to prohibit the flight of arriving aircraft at airspeeds in excess of 250 knots indicated airspeed while in the airspace below 14,500 feet mean sea level within 50 miles of the destination airport (see reference 3). The result of this draft release was both strong support for and opposition against such restrictions. Reference 3 describes the written comments that responded to the draft release, "...one civil aviation organization voiced strong opposition to the proposed rule, emphasizing the economic burden that it felt would be imposed by its adoption. A second organization advocated a speed limit more stringent than the one under consideration, while a third such organization tempered its endorsement with recommendations that the area of applicability be reduced and that the ceiling of applicable airspace be established at 10,000 feet a.m.s.l."

Later, an informal conference among the interested parties was held and further discussions were conducted. The ultimate ruling was a modified version of D.R. No. 61-9, enforcing a 250 knot indicated airspeed restriction with the reduced airspace affected by the rule being all airspace below 10,000 feet m.s.l. and within 30 nautical miles of the destination airport.

The next significant development in the evolution of FAR 91.117(a) was a mid-air collision on March 9, 1967, between an airliner and a private pilot in clear daylight. In the accident report, after acknowledging the inability of "see and be seen" rules to suffice for separation of high-speed VFR traffic and rejecting the potential of increasing the amount of positive control airspace that exists (due to impact of airspace users and economic considerations), the newly-designated Federal Aviation
Administration decided to prescribe the conditions of FAR 91.117(a). The rule was enacted to "...provide a more realistic "see and avoid" environment in the airspace below 10,000 feet mean sea level (MSL) where traffic congestion is greatest..." Furthermore, the National Transportation Safety Board investigating the accident recognized the limitations of the speed restriction and, in the accident report,
recommended "the studying of the feasibility of climb and descent corridors for use by high performance aircraft at major air terminals," as well as, the consideration of collision avoidance systems "until a fail-safe system is developed that applies to all types of aircraft operating under both IFR and VFR weather conditions".

REFERENCES
1. National Transportation Safety Board, "Aircraft Accident Report: Allegheny Airlines, Inc., DC-9, N968VJ and a Forth Corporation, Piper PA-28, N7374J, Near Fairland, Indiana, September 9, 1969," SA-417, Adopted: July 15, 1970. (Report Number NTSB-AAR-70-15)

2. Civil Aeronautics Board, "Aircraft Accident Report: United Air Lines, Inc., DC-8, N 8013U, and Trans World Airlines, Inc., Constellation 1049A, N 6907C, Near Staten Island, New York, December 16, 1960," SA-361, Adopted: June 18, 1962.

3. National Transportation Safety Board, "Aircraft Accident Report: Trans World Airlines, Inc., Douglas DC-9, Tann Company Beechcraft Baron B-55, In-Flight Collision, Near Urbana, Ohio, March 9, 1967," SA-396, Adopted: June 19, 1968.

Cheers,
D.S.
Senior Systems Engineer
Seagull Technology, Inc.