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Seagul1
24th Nov 2003, 14:54
Most ICAO airspace classification has a 250kts below 10000' limit . Commonly it is said that the ATC can suspend this limit. People request for a high sped climb or descend all the time Any ideas or procedures followed by all u guys. Also theres talk of winshields not being certified for bird impacts above 250kts. CHeers :*

expedite_climb
24th Nov 2003, 16:40
In the UK if it is Class A then ATC can lift the limit.

The B757 has a 313 KTS (IAS) birdstrike limit below 8000 feet.

ferrydude
24th Nov 2003, 17:46
FAA Can and does, take a look at Arrivals for the Houston area

Maverfic
24th Nov 2003, 18:14
To quote one European plate:

"When under radar control departing aircraft shall maintain a speed not exceeding 250kt until crossing FL100.
a) The above speed limit may be requested or removed by ATC with the phrase "NO ATC RESTRICTION ON SPEED"
b) Pilots unable to comply with such a limitation shall inform ATC when requesting startup clearance."

Lots of places will have local rulings and routings for noise abatement, terrain clearance etc.

The EGNX plate states:

"To ensure accurate spacing, ATC may request specific speeds and pilots are requested to comply with speed adjustments promptly and within their own operational constraints"

Think that sums it up really: ATC can come out with "No Speed" at which point speed control is yours and all you need do is follow the company profile and observe the birdstrike speed for your a/c type.

HTH.

bookworm
24th Nov 2003, 23:45
In the UK the speed limitation does not apply to flights in class A/B airspace. The limitation may be waived ("suspended") by ATC for flights in class D airspace. It may not be waived by ATC in classes E/F/G airspace.

747FOCAL
24th Nov 2003, 23:53
If the 747 does not exceed 250 kts it will never get above 10,000 ft. :E the earth being round helps a bit as well. :)

TR4A
25th Nov 2003, 03:50
FAA Can and does, take a look at Arrivals for the Houston area

Actually it is for Departures and only while in the Houston Class B airspace. This is the only place in USA unless you have a waiver like Military Jets.

MasterBates
25th Nov 2003, 05:02
expedite_climb says:
__________________________________________________
"The B757 has a 313 KTS (IAS) birdstrike limit below 8000 feet".
__________________________________________________

I´ve never seen that! Is this some sort of operators limit or can we find it in the AOM?


By the way, I´ve always understood the speedlimit below 10.000´ as mandatory in USA (FAR rule) except B airspace, but more flexible in Europe (not as many talibans there).
:8

Maverfic
25th Nov 2003, 05:45
It's in the Boeing 757 Ops Manual; 313 below 8 and they reccommend 250 below 10 at 40 miles inbound in the descent to get the 3 degree profile right for a constant descent approach i.e low thrust low drag low noise low noise complaints low fuel bills;)

Again this is covered in much greater depth on another forum far too clever for me to be browsing.

Canuckbirdstrike
25th Nov 2003, 09:05
It might be worthwhile checking a little more carefully on the information concerning the B757 bird impact speeds. According to the information I have, the speed used for FAR 25 certification is Vc and is reduced linearly to 0.85of Vc at 8,000 feet to achieve a constant TAS for the impact force equation. This would make a 313 IAS at 8000 feet somehwere around 368 IAS at Sea level. This would exceed Vd and or Vmo and by definition Vc will be less than these two speeds.

Further to this the bird weight used for certification is 4 lbs for the windshield and structure and 8 lbs for the empennage. The final certification criteria to consider is that it only considers a single bird. Given that the higher you go the likelihood is you will encounter flocking migratory birds i.e. waterfowl and that the populations are skyrocketing and their average weight is increasing (based on survey data), you might want to think twice about high speed low altitude operations. In the last twelve months there have been a number of serious strikes with geese at speeds below certification speeds that led to windshield penetrations, structural damage and flight crew injury.

As far as engines go, other than the ultra-large engines used on B777 jet engines are only certified to take a single 4 lb bird at the aircraft liftoff speed. Even then they are only required to not catch fire, suffer an uncontained failure, lose the capability of being shutdown, suffer no more than a 25% thrust loss and keep running for 5 minutes.

As for Houston... In 1998 a B727 struck a flock of snow geese (~6.5 lbs) at night at 280 knots IAS. The results were nearly catastrophic - damage to all three engines, leading edge devices, airspeed system. Fortunately there was a Flight Engineer check airman on board to assist with the mutliple failures and the ear-splitting cockpit noise from the damaged radome.

As for the efficiencies to be gained, that is another story that requires careful analysis from a "total system" perspective i.e. if you have an efficient speed of 290 ias for a particular aircraft on day-of-flight, but you are asked to fly at 320 ias. The net result will be an incremental loss in efficiency. A highly complex analysis to say the least.

Approach high speed low altitude operations with great care it might be fatal.

NW1
25th Nov 2003, 09:08
In either the US or the UK, I don't think that ATC can tactically alleviate the 250 below 10,000' limit where it applies except in the defined cases below - generally you need prior written permission. Here are the references:


UK ANO Section 2: Rules of The Air #23Speed Limitation
23 (1) Subject to paragraph (3), an aircraft shall not fly below flight level 100 at a speed which
according to its air speed indicator is more than 250 knots unless it is flying in
accordance with the terms of a written permission of the Authority.
(2) The Authority may grant a permission for the purpose of this rule subject to such
conditions as it thinks fit and either generally or in respect of any aircraft or class of
aircraft.
(3) Paragraph (1) shall not apply to:
(a) flight in Class A airspace;
(b) VFR flight or IFR flight in Class B airspace;
(c) IFR flight in Class C airspace;
(d) VFR flight in Class C airspace or VFR flight or IFR flight in Class D airspace when
authorised by the appropriate air traffic control unit;
(e) the flight of an aircraft taking part in an exhibition of flying for which a permission
under article 61 of the Order is required, if the flight is made in accordance with
the terms of a permission granted to the organiser of the exhibition of flying
under article 61 of the Order, and in accordance with the conditions of a display
authorisation granted to the pilot under article 61 of the Order; or
(f) the flight of an aircraft flying in accordance with the ‘A Conditions’ or the ‘B
Conditions’ set forth in Schedule 2 to the Order.
22 April 2003 And the US FARs:§ 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.
I think the US permits speeds above 250kias beyond 12nms from the coast, but I can't find the reference. Anyone?

604guy
25th Nov 2003, 19:52
In Canada the 250 below 10,000 can NOT be broken by ATC. A few years back I attended a joint conference dealing with a number of operational issues this being one of them. There were a number of operators in attendance that believed it to be true. Transport Canada (the regulator) finally stood up and said that no, this could not be suspended and that it was/is an often held misconception.

av8boy
26th Nov 2003, 01:40
I think the US permits speeds above 250kias beyond 12nms from the coast, but I can't find the reference. Anyone?
If I recall, it is simply the lack of 91.117 applying at a certain point.

§91.1 Applicability.


(a) Except as provided in paragraphs (b) and (c) of this section and §§91.701 and 91.703, this part prescribes rules governing the operation of aircraft (other than moored balloons, kites, unmanned rockets, and unmanned free balloons, which are governed by part 101 of this chapter, and ultralight vehicles operated in accordance with part 103 of this chapter) within the United States, including the waters within 3 nautical miles of the U.S. coast.

(b) Each person operating an aircraft in the airspace overlying the waters between 3 and 12 nautical miles from the coast of the United States shall comply with §§91.1 through 91.21; §§91.101 through 91.143; §§91.151 through 91.159; §§91.167 through 91.193; §91.203; §91.205; §§91.209 through 91.217; §91.221; §§91.303 through 91.319; §91.323; §91.605; §91.609; §§91.703 through 91.715; and 91.903.

(c) This part applies to each person on board an aircraft being operated under this part, unless otherwise specified.

So, 91.117 applies all the way out to 12 miles (91.1(b)), but then drops off. Of course, then there's 91.703...


§91.703 Operations of civil aircraft of U.S. registry outside of the United States.


(a) Each person operating a civil aircraft of U.S. registry outside of the United States shall --

(1) When over the high seas, comply with annex 2 (Rules of the Air) to the Convention on International Civil Aviation and with §§91.117(c), 91.127, 91.129, and 91.131;

(2) When within a foreign country, comply with the regulations relating to the flight and maneuver of aircraft there in force...


91.703(a)(1) makes 91.117(c) apply, but you'll recall that 117(c) applies only to "...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..."

So, assuming you're not in airspace to which 117(c) applies, under the US FARs, that leaves you with Annex 2 (near as I can tell).

Thoughts?

Dave

Iceman49
27th Nov 2003, 08:07
Re: IAH, I believe that the FAA just put a stop to the high speed departures.

Spitoon
29th Nov 2003, 05:56
NW1, para (d) of Rule 23 does not require written permission - just the say-so of the air traffic controller that you're speaking to.

ferrydude
30th Nov 2003, 21:01
!FDC 2/1957 ZHU TX.. EFFECTIVE IMMEDIATELY UNTIL FURTHER ADVISED.
PURSUANT TO A SPECIAL DELEGATION OF AUTHORITY TO GRANT WAIVERS
TO CODE OF FEDERAL REGULATIONS (CFR), PART 91, THE FAA SOUTHWEST
REGION AIR TRAFFIC DIVISION MANAGER HAS WAIVED CFR 91.117A, (250
KNOT SPEED LIMIT) FOR DEPARTING AIRCRAFT IN THE HOUSTON, TEXAS
APPROACH CONTROL AIRSPACE FOR THE PURPOSE OF TESTING THE EFFECT
OF INCREASED DEPARTURE SPEEDS ON THE AIR TRAFFIC CONTROL ENVIRON-
MENT. NOTICE, AIRCRAFT DEPARTING FROM AIRPORTS IN HOUSTON APPROACH
CONTROL AIRSPACE MAY BE AUTHORIZED TO EXCEED THE 250 KNOT SPEED
RESTRICTION CONTAINED WITHIN CFR 91.117A, AT THE DISCRETION OF AIR
TRAFFIC ONTROL (ATC). HOUSTON ATC WILL BE PERMITTED TO ASSIGN/
AUTHORIZE SPEED IN EXCESS OF 250 KNOTS TO DEPARTING AIRCRAFT USING
PHRASEOLOGY "NO SPEED LIMIT" OR "INCREASE SPEED TO (NUMBER) KNOTS."
THIS TEST IS FOR DEPARTURE TRAFFIC ONLY AND MAY BE TERMINATED AT
ANY TIME BY ATC. QUESTION SHOULD BE DIRECTED TO HOUSTON APPROACH
CONTROL, PLANS AND PROCEDURES DEPARTMENT, AT 281-230-8400.