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What's So Special About 10,000 Feet?  
User currently offlineNWADC9 From United States of America, joined May 2004, 4896 posts, RR: 10
Posted (4 years 9 months 4 weeks 1 day 13 hours ago) and read 9355 times:

The 250kt. restriction ends. Personal electronic devices may be used. Why do these things begin at 10,000 feet? What's so special about that altitude?


Flying an aeroplane with only a single propeller to keep you in the air. Can you imagine that? -Capt. Picard
35 replies: All unread, showing first 25:
 
User currently offlineOPNLguy From , joined Dec 1969, posts, RR:
Reply 1, posted (4 years 9 months 4 weeks 1 day 13 hours ago) and read 9295 times:

FAA considers airline ops below 10,000 as critical safety of flight territory.. Portable electronic devices, sterile cockpit, the 250 KIAS limit, exposure to GA aircraft that are not oxygen-equipped --those are just four examples.

[Edited 2009-09-28 13:25:20]

User currently offlineBMI727 From United States of America, joined Feb 2009, 15715 posts, RR: 26
Reply 2, posted (4 years 9 months 4 weeks 1 day 13 hours ago) and read 9253 times:

It is just that pretty much any problem is magnified when you are closer to the ground. Being above 10,000 feet there is more margin for error and the crew can "relax" a bit.

Quoting NWADC9 (Thread starter):
The 250kt. restriction ends.

Usually when planes are below 10,000 they are, of course, near airports. This rule helps keep things from moving too quickly for the controllers and helps put everyone on a level playing field which helps ease sequencing a little bit. I believe that certain airports have their own speed restrictions for certain flight paths to further help in this respect. Also, the rule actually says 250 kts or the aircraft's minimum clean speed, whichever is higher.

Quoting NWADC9 (Thread starter):
Why do these things begin at 10,000 feet?

You forgot that 10,000 feet is usually also the ceiling of the sterile cockpit rule, for the same reasons as above.



Why do Aerospace Engineering students have to turn things in on time?
User currently offlineIAHFLYR From United States of America, joined Jun 2005, 4790 posts, RR: 22
Reply 3, posted (4 years 9 months 4 weeks 1 day 13 hours ago) and read 9178 times:



Quoting BMI727 (Reply 2):
This rule helps keep things from moving too quickly for the controllers and helps put everyone on a level playing field which helps ease sequencing a little bit

Really! What brings you to that conclusion? Is it so the B739 which slows to 250 KIAS won't catch the110 KIAS C172 on approach?



Any views shared are strictly my own and do not a represent those of any former employer.
User currently offlineBMI727 From United States of America, joined Feb 2009, 15715 posts, RR: 26
Reply 4, posted (4 years 9 months 4 weeks 1 day 13 hours ago) and read 9159 times:



Quoting IAHFLYR (Reply 3):
Really! What brings you to that conclusion? Is it so the B739 which slows to 250 KIAS won't catch the110 KIAS C172 on approach?

Which is why I said "helps." All of the jets are doing the same speed roughly, and they make up the bulk of the flights at major airports. And if you think that is bad, just imagine the headaches if your 737 was doing 300+.



Why do Aerospace Engineering students have to turn things in on time?
User currently offlineMrSkyGuy From United States of America, joined Aug 2008, 1214 posts, RR: 3
Reply 5, posted (4 years 9 months 4 weeks 1 day 13 hours ago) and read 9134 times:

Old salt pilots used to call this zone (0-10,000' MSL) "Indian Territory" due to the number of GA pilots which operate in VFR conditions (Indian = Piper named most/all? of their aircraft after Native American tribes).

I always found that little peice of trivia interesting.



"The strength of the turbulence is directly proportional to the temperature of your coffee." -- Gunter's 2nd Law of Air
User currently offlineThrottleHold From South Africa, joined Jul 2006, 655 posts, RR: 1
Reply 6, posted (4 years 9 months 4 weeks 1 day 13 hours ago) and read 9038 times:



Quoting BMI727 (Reply 4):
And if you think that is bad, just imagine the headaches if your 737 was doing 300+.

The rest of the world copes alright! I remember doing 350 Kts at 2000ft in a B747 on the way into Frankfurt.


User currently offlineIAHFLYR From United States of America, joined Jun 2005, 4790 posts, RR: 22
Reply 7, posted (4 years 9 months 4 weeks 1 day 13 hours ago) and read 9015 times:



Quoting BMI727 (Reply 4):
And if you think that is bad, just imagine the headaches if your 737 was doing 300+.

Funny you should mention that.....they'd actually get out of your hair faster.  Smile



Any views shared are strictly my own and do not a represent those of any former employer.
User currently offlinePacific From Hong Kong, joined Mar 2000, 1051 posts, RR: 0
Reply 8, posted (4 years 9 months 4 weeks 1 day 12 hours ago) and read 8887 times:



Quoting ThrottleHold (Reply 6):

http://aviation-safety.net/database/record.php?id=19670309-0

Quote:
Following this accident the FAA issued Advisory Circular 90-32 titled 'Air traffic control and general operations, radar capabilities and limitations'. Also a rule was adopted establishing that all aircraft flying below 10,000ft msl will be limited to a maximum speed of 250kts effective December 15, 1967 to provide a more realistic 'see and avoid' environment.



User currently offlineLowrider From United States of America, joined Jun 2004, 3220 posts, RR: 10
Reply 9, posted (4 years 9 months 4 weeks 1 day 12 hours ago) and read 8864 times:



Quoting ThrottleHold (Reply 6):
The rest of the world copes alright! I remember doing 350 Kts at 2000ft in a B747 on the way into Frankfurt.

Most of the rest of the world does not have the GA environment that the US does. Canada is a notable exception. Even many European airports have speed limit points on the arrivals that require you to slow down as you before you cross them.



Proud OOTSK member
User currently offlineKELPkid From United States of America, joined Nov 2005, 6343 posts, RR: 3
Reply 10, posted (4 years 9 months 4 weeks 1 day 12 hours ago) and read 8862 times:

Two things I can think of:

#1) the vast majority of GA ops happens at 10,000 feet and below, although some does happen above that. I have cruised high performance singles (and a 180 HP 172  Smile ) at 11,500' and 12,500' before...and I have flown a Cessna 210 at 14,000' on Oxygen (using a portable oxygen system). This was because 14,000' was the MEA on the particular airway we were using down in Mexico...

#2) the FAA regards 10,000' as the highest usable (without restrictions) unpressurized altitude. Above 10,000', FAR restrictions start kicking in...  Wink Also, speed limits and (if you're VFR) visibility requirements change at and above 10,000' .



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineMir From United States of America, joined Jan 2004, 21505 posts, RR: 56
Reply 11, posted (4 years 9 months 4 weeks 1 day 11 hours ago) and read 8814 times:



Quoting IAHFLYR (Reply 3):
Is it so the B739 which slows to 250 KIAS won't catch the110 KIAS C172 on approach?

No, but it does help the 172 see and avoid the 739 when both are in the vicinity of the airport.

Quoting KELPkid (Reply 10):
the FAA regards 10,000' as the highest usable (without restrictions) unpressurized altitude. Above 10,000', FAR restrictions start kicking in...

Which FAR restrictions are those? Last I checked, the lowest altitude for oxygen requirements is 12,500.

-Mir



7 billion, one nation, imagination...it's a beautiful day
User currently offlineSpudsmac From United States of America, joined Feb 2008, 296 posts, RR: 0
Reply 12, posted (4 years 9 months 4 weeks 1 day 8 hours ago) and read 8672 times:



Quoting ThrottleHold (Reply 6):

The rest of the world copes alright! I remember doing 350 Kts at 2000ft in a B747 on the way into Frankfurt.

I don't want to be flying in a 172 in echo airspace (where I may fly without talking to anyone!), just climbing through 2000ft and have a 747 come screaming by at 300kias.

Also, correct me if I am wrong, but doesn't positive control airspace (Class Alpha equivalent) start a lot lower in some other parts of the world that may not have this speed restriction? In that case, all the aircraft would be talking to someone and pilots would be vectored out of the way in time.


User currently offlineKeta From Germany, joined Mar 2005, 448 posts, RR: 0
Reply 13, posted (4 years 9 months 4 weeks 1 day 4 hours ago) and read 8567 times:



Quoting BMI727 (Reply 2):
This rule helps keep things from moving too quickly for the controllers and helps put everyone on a level playing field which helps ease sequencing a little bit.

I have read that the 250 kt limit was a protection for the flight envelope against birdstrike. What's true about this?



Where there's a will, there's a way
User currently offlineIAHFLYR From United States of America, joined Jun 2005, 4790 posts, RR: 22
Reply 14, posted (4 years 9 months 4 weeks 22 hours ago) and read 8468 times:



Quoting Keta (Reply 13):
I have read that the 250 kt limit was a protection for the flight envelope against birdstrike

See reply 8, Pacifc posted a link to the "original" reason.

The birdstrike issue is another concern which is aways tossed into the mix, yet in some countries it has not enough an issue for them to slow at 10,000'!



Any views shared are strictly my own and do not a represent those of any former employer.
User currently offlineIllini_152 From United States of America, joined Jan 2001, 1000 posts, RR: 2
Reply 15, posted (4 years 9 months 4 weeks 12 hours ago) and read 8273 times:



Quoting Mir (Reply 11):

Which FAR restrictions are those? Last I checked, the lowest altitude for oxygen requirements is 12,500.

§ 135.89 Pilot requirements: Use of oxygen.

(a) Unpressurized aircraft. Each pilot of an unpressurized aircraft shall use oxygen continuously when flying—

(1) At altitudes above 10,000 feet through 12,000 feet MSL for that part of the flight at those altitudes that is of more than 30 minutes duration; and

(2) Above 12,000 feet MSL.

(b) Pressurized aircraft. (1) Whenever a pressurized aircraft is operated with the cabin pressure altitude more than 10,000 feet MSL, each pilot shall comply with paragraph (a) of this section.

(2) Whenever a pressurized aircraft is operated at altitudes above 25,000 feet through 35,000 feet MSL, unless each pilot has an approved quick-donning type oxygen mask—

(i) At least one pilot at the controls shall wear, secured and sealed, an oxygen mask that either supplies oxygen at all times or automatically supplies oxygen whenever the cabin pressure altitude exceeds 12,000 feet MSL; and

(ii) During that flight, each other pilot on flight deck duty shall have an oxygen mask, connected to an oxygen supply, located so as to allow immediate placing of the mask on the pilot's face sealed and secured for use.

(3) Whenever a pressurized aircraft is operated at altitudes above 35,000 feet MSL, at least one pilot at the controls shall wear, secured and sealed, an oxygen mask required by paragraph (b)(2)(i) of this section.

(4) If one pilot leaves a pilot duty station of an aircraft when operating at altitudes above 25,000 feet MSL, the remaining pilot at the controls shall put on and use an approved oxygen mask until the other pilot returns to the pilot duty station of the aircraft.



Happy contrails - I support B747Skipper and Jetguy
User currently offlineBMI727 From United States of America, joined Feb 2009, 15715 posts, RR: 26
Reply 16, posted (4 years 9 months 4 weeks 12 hours ago) and read 8259 times:



Quoting Keta (Reply 13):
I have read that the 250 kt limit was a protection for the flight envelope against birdstrike. What's true about this?

It is certainly a benefit, but I don't know if that is why the rule was enacted. I do know that some birdstrikes occur as high as 30,000.



Why do Aerospace Engineering students have to turn things in on time?
User currently offlineMir From United States of America, joined Jan 2004, 21505 posts, RR: 56
Reply 17, posted (4 years 9 months 4 weeks 11 hours ago) and read 8235 times:



Quoting Illini_152 (Reply 15):
§ 135.89 Pilot requirements: Use of oxygen.

Fair enough. I'm not familiar with 135 regs.

-Mir



7 billion, one nation, imagination...it's a beautiful day
User currently offlineBraniff747SP From United States of America, joined Oct 2008, 2963 posts, RR: 1
Reply 18, posted (4 years 9 months 3 weeks 6 days 10 hours ago) and read 7997 times:

But why the electric stuff rule at 10K??


Happy Contrails!



The 747 will always be the TRUE queen of the skies!
User currently offlinePGNCS From United States of America, joined Apr 2007, 2820 posts, RR: 45
Reply 19, posted (4 years 9 months 3 weeks 6 days 8 hours ago) and read 7959 times:



Quoting ThrottleHold (Reply 6):
The rest of the world copes alright! I remember doing 350 Kts at 2000ft in a B747 on the way into Frankfurt.

I wish you luck when you hit a goose.


User currently offlineJeffry747 From United States of America, joined Jun 2005, 963 posts, RR: 2
Reply 20, posted (4 years 9 months 3 weeks 4 days 12 hours ago) and read 7700 times:

The other day I flew SDF-CVG in an EMB-145. According to FlightAware.com, we cruised at 9,000ft and 286kts. I am pretty sure the minimum clean speed of the EMB-145 is less than 250kts. How is it we were allowed to go faster than the speed limit below 10k ft. Is it legal?


C'mon Big B, FLY!
User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 21, posted (4 years 9 months 3 weeks 4 days 12 hours ago) and read 7699 times:
AIRLINERS.NET CREW
DATABASE EDITOR



Quoting Jeffry747 (Reply 20):
According to FlightAware.com, we cruised at 9,000ft and 286kts.

Two thoughts:

- As great a site as FlightAware is, I'd be careful not to overestimate the accuracy of its data
- Flightaware records groundspeed. Not indicated airspeed.

2H4



Intentionally Left Blank
User currently online9VSIO From United Kingdom, joined Dec 2006, 708 posts, RR: 2
Reply 22, posted (4 years 9 months 3 weeks 4 days 11 hours ago) and read 7667 times:
Support Airliners.net - become a First Class Member!

UK has a limit of 250 below 10k, but I believe ATC can remove that restriction.


Me: (Lining up on final) I shall now select an aiming point. || Instructor: Well, I hope it's the runway...
User currently offlineZappbrannigan From Australia, joined Oct 2008, 247 posts, RR: 0
Reply 23, posted (4 years 9 months 3 weeks 3 days 3 hours ago) and read 7482 times:



Quoting Spudsmac (Reply 12):
I don't want to be flying in a 172 in echo airspace (where I may fly without talking to anyone!), just climbing through 2000ft and have a 747 come screaming by at 300kias.

Also, correct me if I am wrong, but doesn't positive control airspace (Class Alpha equivalent) start a lot lower in some other parts of the world that may not have this speed restriction? In that case, all the aircraft would be talking to someone and pilots would be vectored out of the way in time.

Is that possible in the US? Here in Aus, Class E airspace doesn't exist anywhere below 8,500', and generally steps up to a lower limit of FL180, above which is Class A.

Until you hit some Class E departing a major aerodrome, all airspace is either Class G unrestricted, or Class C above the Class G. VFR aircraft operating in Class E airspace do not require a clearance, but do require a Mode-C transponder operating - meaning the chances of coming across a random 747 are pretty low. And this can't happen at 2,000' here. A slightly higher risk is the IFR aircraft maintaining 10,000 flying head-on with the VFR aircraft at 9,500 in Class E, and the controller trying to sort it out, as has happened to me a few times - although this is no different to the same thing in unrestricted airspace. The big jets are kept well clear.

Our Class A doesn't exist below FL180 anywhere.


User currently offlineLowrider From United States of America, joined Jun 2004, 3220 posts, RR: 10
Reply 24, posted (4 years 9 months 3 weeks 2 days 22 hours ago) and read 7430 times:



Quoting Zappbrannigan (Reply 23):
Is that possible in the US?

Yes. Many parts of the country, class E may start as low as 700 ft agl. At many small airports served by instrument approaches, it goes down to the surface so as to protect the area needed to conduct the approach during IFR ops. If there is no airway, transition, approach, or airport requirement, it may start aa high as 14,500.

Quoting Zappbrannigan (Reply 23):
all airspace is either Class G unrestricted

Our class G is designated uncontrolled, and starts at the surface and may go as high as 14,500.

Quoting Zappbrannigan (Reply 23):
Class C

Class B, C, and D are all associated with airport and a portion surrounding the airport will go to the surface. All of class D goes to the surface.

Quoting Zappbrannigan (Reply 23):
Our Class A doesn't exist below FL180 anywhere.

Nor does ours.



Proud OOTSK member
25 9VSIO : The UK has plenty of class A airspace at lower altitudes. In fact, it can be extremely trying to navigate between the huge chunks of controlled airsp
26 Zappbrannigan : Interesting. Class E here only serves higher-capacity airports - 98% of the airports here which have published approaches are in Class G airspace, an
27 Hotelmode : Doesnt flight aware use groundspeed or at least true air speed? 240 kts indicated air speed is roughly 286 kts TAS or groundspeed at 9000ft anyway. A
28 IAHFLYR : And don't forget, groundspeed also includes the winds aloft in the total number. Class E also goes to the surface.
29 Mir : Flightaware looks at groundspeed (as does ATC). 286kts sounds about right for 250kias at that altitude. In the US, Class E generally starts at 1200'
30 IAHFLYR : Oh come on Mir, don't tell the public that ATC looks at groundspeeds.........dang it!!! Just curious, how many have you hit in the air and how many t
31 Lowrider : If you could be bothered to read to the second sentence you would have seen...
32 IAHFLYR : Excuse me, what was I thinking other than the fact I wasn't referencing the same paragraph as you indicate.
33 MPDPilot : I thought I would share my understanding of the 10,000' significance. There are some rather significant atmospheric changes that occur above 10,000'.
34 Ferrypilot : Just as a matter of interest do you happen to know if your windscreen would deflect a Goose at 250knots.
35 IAHFLYR : A question that I've asked a few times and even a time or two on this site, still waiting to hear the answer if anyone does know?
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