250 Knots IAS below 10,000 feet - is it adhered to?

Discussion in 'Flight Following' started by Lndwarrior, Apr 4, 2019.

  1. Lndwarrior

    Lndwarrior Pre-takeoff checklist

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    I fly a lot thru northern California Central Valley. Over the past year (including last week) I have seen (a little too close for comfort) mulitple corporate jets exceeding 250 knots indicated on my adsb readout below 10,000 feet.

    Is this an erroneous interpretion of mine regarding the adsb read-out I am seeing - or is the 250 knot limit not enforced?

    Or?
    TIA,
    Gary
     
  2. Bellanca_Pilot

    Bellanca_Pilot Pre-Flight

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    How are you seeing their indicated speed?


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  3. Greg Bockelman

    Greg Bockelman Administrator Management Council Member

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    What you are seeing is ground speed. The limit is for indicated airspeed.
     
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  4. Bellanca_Pilot

    Bellanca_Pilot Pre-Flight

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    Also the speed restriction is not applicable in B. But bottom line, they push the envelope. Movers and Shakers got places to be.


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  5. Greg Bockelman

    Greg Bockelman Administrator Management Council Member

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    250 below 10 applies in B also.
     
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  6. Bellanca_Pilot

    Bellanca_Pilot Pre-Flight

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    Correct, I was thinking of the 200 limit.


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  7. Clip4

    Clip4 En-Route

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    This, I have heard countless crews tell ATC they tossed the anchor out when asked by ATC about their speed.
     
  8. JC150

    JC150 Pre-takeoff checklist

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    The jet I fly will slow to 250 before 10,000 however the auto throttles can be a little sluggish correcting and I’ve seen 265 indicated with a wind shift before. No big deal as long as it’s correcting
     
  9. EdFred

    EdFred Touchdown! Greaser! PoA Supporter

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    "Unless otherwise authorized..."
     
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  10. luvflyin

    luvflyin Final Approach

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    ain't no way your adsb is telling you their indicated airspeed
     
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  11. ktup-flyer

    ktup-flyer En-Route

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    You might as well be watching them on flightaware.
     
  12. MauleSkinner

    MauleSkinner Final Approach

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    Emphasis mine:
    Apparently ATC and the Administrator aren’t the same entity.
     
  13. Cooter

    Cooter Pattern Altitude

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    The military has exemptions. In my experience, the rule was mostly ignored and the waiver not strictly followed.
     
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  14. TK211X

    TK211X Pre-takeoff checklist

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    Back before I got my Private Pilot cert. I used to go out to KTPA lounge area with my handheld and follow aircraft from ground to tower and then over to departure. It surprised me how many times controllers said "Do not exceed 250kts below 10k" or something along those lines to departing aircraft.
     
  15. Lndwarrior

    Lndwarrior Pre-takeoff checklist

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    Thanks partly what i was wondering.

    Can you explain the difference between what i am seeing on the adsb compared to what they may be seeing as IAS?

    And for the cynical readers, Im serious about learning here, I dont know the answer.
     
  16. Lndwarrior

    Lndwarrior Pre-takeoff checklist

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    If you have time, can you explain what you mean?
     
  17. ktup-flyer

    ktup-flyer En-Route

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    You're seeing groundspeed. The only people that know IAS are the people in the cockpit.
     
  18. kath

    kath Line Up and Wait

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    ADS-B works through GPS, which knows how your position (relative to the ground) is changing and how fast. It doesn't know anything about how the air might be moving. Flightaware reads the same thing: ground track.
    And airspeed indicator knows how fast you're moving through the air. It doesn't know anything about where the ground is.
    If there's wind, they'll be different.
     
  19. iamtheari

    iamtheari Pattern Altitude

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    In a standard atmosphere, an indicated air speed of 250 knots at 10,000 feet is a true airspeed of 291 knots. Add tailwinds and you could see a GPS ground speed of 320 knots or more for a plane with an airspeed indicator pointing straight at 250.
     
  20. Lndwarrior

    Lndwarrior Pre-takeoff checklist

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    Thank you for the explanation.
     
  21. Lndwarrior

    Lndwarrior Pre-takeoff checklist

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    Ok, now i get it. Thanks!
     
  22. LongRoadBob

    LongRoadBob Cleared for Takeoff

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    As long as one knew the winds at their altitude and temp one could calculate the IAS, at least fairly accurately right?
     
  23. flyingron

    flyingron Touchdown! Greaser!

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    THey are if the administrator delegates his authority. Same thing that allows the FSDO guys to determine what data is "acceptable to the administrator" on mods.
     
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  24. Spring Ford

    Spring Ford Pre-takeoff checklist

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    Not all ads-b installations emit the position and in that case the provider can use Multilateration (MLAT) to locate the aircraft. This is not as accurate as GP and results in errors that may give erroneous calculated speeds. I'm not sure how many aircraft capable of more than 250 knots will not emit GPS.

    e.g.
    See the "Data source - MLAT" and wobbly speed graph.
    upload_2019-4-5_8-27-53.png
     
  25. AnthonyS1

    AnthonyS1 Pre-Flight

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    When I was at the airlines we never ever intentionally went over 250KIAS below 10k.
     
  26. bflynn

    bflynn En-Route

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    Wind.
     
  27. MauleSkinner

    MauleSkinner Final Approach

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    And there have been cases where the Administrator delegated his authority with exceptions to the 250-knot rule in Class B below 10,000...but the authority was specifically given and then rescinded. I haven’t heard of any others with regard to speed limits.
     
  28. Greg Bockelman

    Greg Bockelman Administrator Management Council Member

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    And true airspeed vs indicated airspeed. True can be quite a bit higher than indicated at 10,000 feet.
     
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  29. Seanaldinho

    Seanaldinho Pattern Altitude

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    Also keep in mind, about the only person who can report you is the controller working you. Generally the controller isn't going to care (or have time to care) if you're a little over speed and they will issue a speed restriction if they need to ensure separation.
     
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  30. Grum.Man

    Grum.Man Pattern Altitude

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    I've never been questioned outside of Bravo airspace for exceeding 250. I have been questioned a few times while inside the lateral bound but under the floor for exceeding 200. They usually let it slide when I tell them I am a piston airplane and cannot go down and slow down.
     
    Last edited: Apr 5, 2019
  31. Dave Theisen

    Dave Theisen En-Route PoA Supporter

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    ????? Inside the Bravo you can do 250, it’s UNDER the Bravo you have to do 200.
     
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  32. Larry in TN

    Larry in TN Cleared for Takeoff

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    The speed limit inside Class B airspace (below 10,000' MSL) is 250 kias.
     
  33. Grum.Man

    Grum.Man Pattern Altitude

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    You guys are correct, by inside I was thinking inside the mode C veil but I was still under the Bravo floor.
     
  34. kayoh190

    kayoh190 En-Route PoA Supporter

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    I think people tend to get confused because the ceiling of most Class B airspace is 10,000’. But to be clear, there is no speed limit for Class B airspace.

    Also, I haven’t witnessed at any point in my professional career - either as a crewmember or jumpseater - someone intentionally go faster than 250 below 10,000’ unless we were either far enough out over the water to be legal, or adding a few knots to get the autopilot to lower the nose a little more while in Level Change or IAS. Never just to ‘go fast’.
     
    Last edited: Apr 5, 2019
  35. Velocity173

    Velocity173 Touchdown! Greaser! PoA Supporter

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    And if they do care (separation), then they’ll just assign a speed restriction. I always went with vectors vs speed adjustments for the occasional speeder. That works best in the non SID / STAR environment.
     
  36. Tantalum

    Tantalum En-Route

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    Was the Concorde authorized by the administrator to exceed the speed rule? I feel like 250 knots would have been on the slower side for the Concorde
     
  37. GeorgeC

    GeorgeC En-Route PoA Supporter

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    91.117 (d)
     
  38. Tantalum

    Tantalum En-Route

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    "(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."
    Which seems beautifully vague. I'm sure the Concorde can be operated "safely" under 250. Wonder what the official SOP is or if there is a specific Vspeed this is referring to, like Va for instance. If we go by certain minimum speeds then a fully laden swallow (I mean 747) will have a minimum flaps clean speed well above 250 knots.. do they climb to 10K with flaps out, or do they accelerate up to 280 or so and clean up?

    Also nuts, is the sheer speeds that jet planes fly. If I recall correctly from the days I was an even bigger aviation dork and had more free time on my hands the PMDG 747 climb speeds were 250 knots to 10K then 340 knots to FL250 transitioning to Mach 0.84 for the remainder of the climb. 340 knots indicated for a transport civilian jet. NUTS
     
  39. Turningfinal

    Turningfinal Pre-takeoff checklist

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    I listen to departures out of ORD and quite often Asian bound heavies will ask for authorization to exceed the 250 knot speed restriction.
     
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  40. Tantalum

    Tantalum En-Route

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    Which implies that "ATC" and "the Administrator" are ubiquitous