My instructor told me I had to report change in airspeed regardless. I
found this in the AIM:

Section 3. En Route Procedures

5-3-1. ARTCC Communications

snip

5-3-3. Additional Reports

a. The following reports should be made to ATC or FSS facilities
without a specific ATC request:

1. At all times.

(a) When vacating any previously assigned altitude or flight
level for a newly assigned altitude or flight level.

(b) When an altitude change will be made if operating on a
clearance specifying VFR-on-top.

(c) When unable to climb/descend at a rate of a least 500 feet
per minute.

(d) When approach has been missed. (Request clearance for
specific action; i.e., to alternative airport, another approach, etc.)

(e) Change in the average true airspeed (at cruising altitude)
when it varies by 5 percent or 10 knots (whichever is greater) from that
filed in the flight plan.



FWIW

----------------------------------------------------------


"C J Campbell" wrote in message
...

"Craig Prouse" wrote in message
...
| In article aqnLb.1278$na.1288@attbi_s04, Newps
| wrote:
|
| Robert Moore wrote:
|
|
| If you have "advised" ATC of a change in TAS, they recompute your
ETA.
|
| ATC does no such thing. You tell a controller that you are going 20
| knots slower/faster than you put on your flight plan the controller
| could not possibly care less. In one ear and out the other.
|
|
| Don Brown, according to his column today, seems to pay attention to such
| details.
|
| http://www.avweb.com/news/columns/186442-1.html

Don Brown's gripe appears to be about what he was handed from other
sectors,
not about what airspeed the pilot reported.

Correct me if I am wrong, but I thought you only reported a change in
airspeed or ETA if you were in a non-radar environment?