Adherence to Mach Speed
 

Having a discussion with a fellow pilot about the specific rules/regs governing the adherence to mach # in areas that use Mach Number Technique. The Jep references I have, say simply that Assigned Mach Number must be "strictly" adhered to.

Can someone provide me with the end all reg on this with the refernce Document included.

I've got all the opinions I need on this - and I'm also not interested in "practical" applications of the regs - which I am not discounting as important - just not what I need right now.

BTW - I've heard - somewhere laying around in the ICAO Docs is a statment that adherence must be within .005 of assigned Mach Number - ie - you're assigned .79 = you can drift between .785 and .795 without advising ATC.

I've got an entire bottle of wine riding on this - so you can imagine how important this is.

Thanks for any information.

LL

I thought the 'atlantic'error was to be within 0.10 of the assigned Mach(it pretty tough to keep even the 'selected 'speeds that close with Temp variations)
cheers;)

Sorry that should have been: M0.010(6knots)...
Cheers:rolleyes:

Huh! Try keeping the assigned Mach number that close on a bumpy Atlantic crossing, what a joke. I'm told by my friend who flies the 777 that the speed's all over the place in moderate turbulence...just like the rest of us!

When set at .85 in Thrust Management/Auto Throttle mode, the Mach indicator rolls from .843 to .858, back and forth all day. I'm hardly concerned. :p

concur with m&v: +/- M.01

i'll have a hunt around for a reference for you

Staying within 5% of FPL speeds is what leapt into my brain. No idea if its right or not, I'll look it up.

CPB

Aerad Flight Information Supplement ATC 43:
TRACK AND ETA
Adherence to Flight Plan
12.2.3. Change of True Airspeed (TAS).
(a) If at any time a change in TAS of five percent of that given in the Flight Plan, is premeditated, with the intention that the revised TAS is to be maintained for the remainder of the flight or portion thereof, the pilot must notify the appropriate Oceanic Centre before making the change or as soon as possible thereafter.
(b) Pilots will adhere to the true Mach number approved by ATC and shall request ATC approval before making any change thereto. If essential to make an immediate temporary change in the Mach number (e.g. due to turbulence), ATC shall be notified as soon as possible that such a change has been made.
(c) ATC will asume that the last assigned MACH number will be maintained in CRUISE Flight and in any climbs or descents made in the course of the Flight, unless advised by the pilot concerned.

I am going to training this week, so I thought I would look into this question. Below is from the US Aeronautical Information Manual (AIM) Chapter 4.

4-4-11. SPEED ADJUSTMENTS
a. ATC will issue speed adjustments to pilots of radar-controlled aircraft to achieve or maintain required or desire spacing.

b. ATC will express all speed adjustments in terms of knots based on indicated airspeed (IAS) in 10 knot increments except that at or above FL 240 speeds may be expressed in terms of Mach numbers in 0.01 increments. The use of Mach numbers is restricted to turbojet aircraft with Mach meters.

c. Pilots complying with speed adjustments are expected to maintain a speed within plus or minus 10 knots or 0.02 Mach number of the specified speed.

I'm uncertain of its applicability outside of the USA.