This thread went off on a tangent because of there's a difference between declining a offered clearance and deviating from an obtained clearance

.

Of course a pilot may decline any clearance offered.

 

However, once a clearance is obtained it may not be deviated from except in accordance with §91.123. ATC would be in an impossible position if it couldn't assume that aircraft would adhere to the clearance but could go wandering about the sky at the pilot's whim.

 

So, how many times do I need to clarify this for you?  I think I've proven that I'm willing to.  To be honest, nobody went off on this tangent about ATC clearances until you brought it up, in what I'm guessing was a way to discredit the argument about the 91.117d exemption.

 

Even so - again - your argument holds no water, for a few reasons:

1. In the case clearance is obtained and it is invalid (as it is unsafe for the operation), then it is invalid.  The pilot does not have to comply with it, and it therefore has no 91.123 enforcement.  You're asserting this is a deviation and this is not true.  The pilot must advise ATC, however, who will then provide further instruction (an amended clearance).  Again, there was no deviation by not following the instruction.
2. Obtaining an amended clearance is a valid way to continue to conduct operations.  Nobody is questioning that.
3. ATC is not in an impossible situation because of how they're taught to operate.  The whole fact that the IFR system is predicated on losing communication with the pilot (who would then by flying "at the pilot's whim") underscores the fact that positive separation isn't all about telling people to do things.  Without having seen some of the training controllers go through, though, one can't fully understand that, though.
4. Remember that I didn't just exempt pilots from listening to ATC at all.  I only exempted - in accordance with the FAR and AIM - unsafe instructions.  So, no, pilots wouldn't just be flying around on their own whim.  You can only disregard instructions in an emergency state, or when those instructions compromise the safety of flight.

Then what does this mean?

 

 

91.123   Compliance with ATC clearances and instructions

 

(a) When an ATC clearance has been obtained, no pilot in command may deviate from that clearance unless an amended clearance is obtained, an emergency exists, etc, etc

I was once told by my instructor, no matter what ATC clears you for, you are to AVIATE, NAVIGATE, then COMMUNICATE. 

 

If ATC gives you a clearance and you accept it, you still fly your aircraft in a SAFE manner, you navigate your aircraft in a SAFE manner then you talk to ATC and inform them what is going on, emergency or not.

 

I am not saying you do not comply with ATC, because if you do not you are in violation of 91.123, but you fly your aircraft first.

 

This is just my 2 cents.

Get the ITVV video of the Virgin 747, and watch. They accelerate to nearly 300 knots....below 10000ft.

 

'nuff said.

 

Best regards,

Robin.

Get the ITVV video of the Virgin 747, and watch. They accelerate to nearly 300 knots....below 10000ft.

 

'nuff said.

 

Best regards,

Robin.

 

I  think you missed this earlier post

 

 

No because they get it on first contact, 46:50 in.

 

"VIR19 squawk ident there is no atc speed restriction".

Well there you go. Was a regular occurance with Concorde, too (and other aircraft).

 

I guess the best way is to listen to LiveATC.net where there is a lot of 747 traffic going long-haul, and listen to the comms. Together with FlightRADAR24.com you should be able to see who is doing what speed below 10000 ft.

 

Here is an A320 doing 285 kts below 10000 ft:

 

http://img585.imageshack.us/img585/9547/kj5n.png

 

EDIT: For some silly reason .png format is not allowed to be used as an image.

 

Best regards,

Robin.

 

 

Was a regular occurance with Concorde

 

Concorde was exempted from many rules in the UK - including noise.

Not exempted from speed...not at all. There was an unwritten rule that Concorde "just went faster than everything else", and had special procedures (much to the chagrin of other airlines who would sometimes get bumped to let Concorde in). They made "no speed" as standard for Concorde as they did "cleared for takeoff".

 

Best regards,

Robin.

I'm not sure what FR24 shows but most radars show GS and not IAS, however speed restrictions are based on IAS.

 

My point being that you should be carefull in assuming speed based on the speed off a radar picture.

 

Obviously if FR24 uses the IAS downlink from the mode S and not the GS donwlink then the above isn't valid when using FR24.

Then what does this mean?

 

 

 

How many different ways do I need to state that 91.123 is still subject to safe instructions?  I think I've said it about 4 different ways now?

 

The FAA itself has determined, as outlined in the AIM, that an unsafe command from ATC is invalid.  Ergo, if a controller issues a command that would put the aircraft in unsafe situation, the command is invalid.  This means that 91.123 never even comes into play.  It's as if the command were never stated.

 

The AIM does go on to say that the pilot does have a responsibility to report the inability to execute the instruction, and to request another clearance.  This serves two purposes:

1. To alert ATC that the pilot cannot comply, and will continue via the last assignment (whatever that may be)
2. To alert ATC to provide alternate instructions, or tactically adjust the plan for that aircraft

 

 

My point being that you should be carefull in assuming speed based on the speed off a radar picture.

 

Exactly - up until the newer displays come into play for controllers, they can only look and see "oh hey, that one guy's '250' is different from that other guy's '250'...someone isn't playing by the rules!"

 

 

How many different ways do I need to state that 91.123 is still subject to safe instructions?

 

How many times do I need to state that if a pilot's obtained a clearance then 91.123 does apply.

Right... Let's take the following scenario:

ATC asks you to fly heading 090, straight into a cloud a few miles away.

Without you knowing, for whatever reason, there's a mountain behind that very cloud. The controller doesn't realise, again for whatever reason, that he turned you towards the mountain.

When you fly through the cloud, and see the mountain, you're not going to take evasive action, you'll just be waiting for another ATC clearance?

Aviate, Navigate, Communicate.

 

 

When you fly through the cloud, and see the mountain, you're not going to take evasive action, you'll just be waiting for another ATC clearance?

 

No. That's an emergency so obviously you're going to deviate.

 

Read what I actually said in post #120

 

 

 

However, once a clearance is obtained it may not be deviated from except in accordance with §91.123. ATC would be in an impossible position if it couldn't assume that aircraft would adhere to the clearance but could go wandering about the sky at the pilot's whim.

So in this scenario, according to you, there are only two options:

1. Declare an emergency.

2. Plow into the mountain.

 

There's not a single reason why this would be an emergency. Either you change direction, or you pull up, and you advise ATC about your actions. Unless you're really, really close to the mountain in question, there's not a single reason to call this an emergency.

 

Use some common sense, that's exactly what the grey area in the FARs is there for.

 

You must be fun at parties...

 

 

1. Declare an emergency

 

Where do the CFRs say an emergency has to be declared? Read  91.123  in full.