FAR 91.117c Speed Under B

r9s

Newcomer
Dec 26, 2010
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how aware are pilots of this requirement. most air carriers comply. some ask to go faster. but many (not all or most) of the GA guys flying gulfstreams, falcons, ect. just come blasting out of the airport apparently unaware of the FAR. our DP are designed with the speed requirement in mind and so sometimes i am scrambling to keep control of my departure flow.
 

StuSEL

Moderator
Aug 23, 2009
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Questions about this are asked on almost every FAA written test that private, instrument, commercial, and CFIs take. Pilots who claim they are unaware of the rule are lying or have terrible memory. Before you call the FSDO, though, make sure you're aware of what your winds aloft are, otherwise you'll look like the idiot. :p
 

rooster

Trusted Contributor
Sep 6, 2009
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Questions about this are asked on almost every FAA written test that private, instrument, commercial, and CFIs take. Pilots who claim they are unaware of the rule are lying or have terrible memory. Before you call the FSDO, though, make sure you're aware of what your winds aloft are, otherwise you'll look like the idiot. :p
I tried to explain winds aloft to a trainee last week and he gave me a blank look for a good 5 minutes...I wanted to beat him with his PCG...
 
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charliezuluatc

Guest
I have seen cheap deal occur in the jet stream where you turn a plane, 30 degrees and looses 100 knots and bam up the six. The. There where an md80 gets launched infront of an airbus. Tell the md80 to do 280 or 290, the airbus 250 in a climb. Begging upstairs sector for higher. When launching aircraft you must almost be mindful of performance. Some planes are exempt from the speed rules. Tell a t 38 to do 170, listen to their laugh.
 
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charliezuluatc

Guest
It will be very hard to turn in a pilot for busting the speed rules. They can come back and say we only went 20 kts over for safety. The winds, weather or whatever, conditions were ripe for us to bust it.
 

r9s

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Dec 26, 2010
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Questions about this are asked on almost every FAA written test that private, instrument, commercial, and CFIs take. Pilots who claim they are unaware of the rule are lying or have terrible memory. Before you call the FSDO, though, make sure you're aware of what your winds aloft are, otherwise you'll look like the idiot. :p
that is good to know. when necessary i have advised pilots that speed requirement compliance is expected under the bravo. it is usually too late at this point and i have to vector some s turns for spacing until i get their speed back - but at least they have been reminded for next time.

how does FSDO go about enforcement? if tower launches 10 flights in a row all like types and everyone is 200 kts perfectly intrail but pilot number 4 is 40kts faster loosing separation - it would seem unreasonable for a tailwind to only affect him. even if i ask them to say airspeed they will probably realize at that point and say "200kts".

in any case i am not interested in "gotcha" but i am interested in compliance. which prompted the original question. glad to know that this rule should be well known to pilots.
 
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charliezuluatc

Guest
Exactly and if they did say the pilot broke the role, the pilot can say for safety, aircraft performance and get out of it.
 

mbalunda

Epic Member
Jan 31, 2009
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If I turned someone in every time they went over 250 kts all I'd be doing is paper work. The international flights of ORD start doing like 290 kts when they pass 6k feet. Not to mention they are below 10k and the sid is published for all aircraft to do 250 kts until advised.
 

digitalpilot

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Feb 7, 2016
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If I turned someone in every time they went over 250 kts all I'd be doing is paper work. The international flights of ORD start doing like 290 kts when they pass 6k feet. Not to mention they are below 10k and the sid is published for all aircraft to do 250 kts until advised.
Question for ATC guys...

The FAR's clearly state... below 10,000FT 250 Kts unless the "min safe speed" is above 250!
Now for most "Heavy" and "Super" cat a/c this will mean that our Flap up (min clean) speed is greater than 250 Kts.
My question is:
What is considered "min safe speed"?
What does ATC expect from the big heavy and super cat a/c's to fly below 10,000ft?

Please help clearify. Thanks you.
 

BeaconSlash

Trusted Member
Aug 19, 2011
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Question for ATC guys...

The FAR's clearly state... below 10,000FT 250 Kts unless the "min safe speed" is above 250!
Now for most "Heavy" and "Super" cat a/c this will mean that our Flap up (min clean) speed is greater than 250 Kts.
My question is:
What is considered "min safe speed"?
What does ATC expect from the big heavy and super cat a/c's to fly below 10,000ft?

Please help clearify. Thanks you.
The pilot is the only one that ultimately will decide minimum safe speed.

If you can't meet the restrictions of a procedure (like maintain 250 knots), then advise ATC prior to departure (clearance delivery preferable IMO), preferably with the min safe speed you can and will maintain. ATC should/will coordinate approptiately and adjust traffic flow as necessary to accomodate. Long as you tell us, you shouldn't be looked at for a pilot deviation.

Pretty simple...
 

digitalpilot

Newcomer
Feb 7, 2016
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Thanks guys, I really appreciate your response! I will pass on this message to our flight ops... I know that a lot of our pilots do not tell ATC what their Min Clean Speed is on the PDC or when speaking with Dep Control... we need to change they way we are currently operating.
Cheers!
 

BeaconSlash

Trusted Member
Aug 19, 2011
367
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Dare I ask... who do you work for where the dispatchers/flight ops wouldn't think of this on their own?

Make a throwaway or something and log in anonymously if you're worried, but it's a little scary to me that an aircraft operator that owns heavies or other aircraft that aren't your "typical" fleet isn't aware of how to deal with ATC issues...

Secrets are never good in our job... and most of the FARs are rather flexible as long as you tell someone and get approval to deviate from the norm ahead of time, especially in the ATC realm.
 

mbalunda

Epic Member
Jan 31, 2009
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Question for ATC guys...

The FAR's clearly state... below 10,000FT 250 Kts unless the "min safe speed" is above 250!
Now for most "Heavy" and "Super" cat a/c this will mean that our Flap up (min clean) speed is greater than 250 Kts.
My question is:
What is considered "min safe speed"?
What does ATC expect from the big heavy and super cat a/c's to fly below 10,000ft?

Please help clearify. Thanks you.
In reality they should maintain the published speed unless like you said it's below their minimum. No one has a problem when a plane has to go faster as long as we're aware of it and they don't do it on their own.

I vividly remember a 3 AC stream with 777, 777, and a 747. I assigned the first AC 300+ on contact to keep him in front, and gave the second one 280 just to build room. As the 3rd AC climbed I planned on issuing 280 to the 747 as well, which is generally a safe speed for the heavies. And then through 10k the guy just keeps going faster and faster before I ever issued any speed. Now I'm just curious to what he's doing, so I question the guy and he freaks out about how he can't do 250 knots blah blah, so I said what's your airpseed?(At this point his groundspeed is 70 knots higher than the AC 6.5 miles in front of him, +/- 800 feet). His reply? 340 knots! That's about the only pilot I've ever yelled at. I understand when they cheat up to 280 or even 290 knots, but 340 knots is FAR beyond anything that could be considered their minimum safe speed.

I always make it a point to give them normal speed on contact if traffic permits because I know they're working with a different set of parameters.
 

digitalpilot

Newcomer
Feb 7, 2016
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See the problem with this operator is not that they do not know how to deal with ATC issues, it's more a operational culture of we do what we like attitude! So when ever I am in the operating seat, I do my part of informing and educating the Jr pilots members of how to handle this type of situation. But in a big company with old cultural (bad) habits it will take some time to shift!
I am glad to have found this forum... now i feel that at least i can ask the questions... get the ATC perspective and bring it back to the flight deck in an informed manner!

Thanks you guys.
 

digitalpilot

Newcomer
Feb 7, 2016
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Okay another Speed related question...

Lets say we are descending through 20000 ft for 15000 ft at 300Kts and ATC tells us to slow to 250Kts. My question is... How fast is ATC expecting us to slow down in? I cannot find this answer anywhere... any idea would be welcome...

Is it reasonable to say that in this example a change of 50 Kts of speed takes 60 secs?

Thanks!
 

NovemberEcho

Epic Member
Dec 8, 2010
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Long Island
Generally I figure about 10kts a mile, but that's all under 10k, so it might be more like 10kts every 2-3 miles over 10k given the thinner air and faster speeds