How do you interpret...

When filling IFR, there are two boxes you put numbers in, AIRSPEED and
TIME ENROUTE.

These go back to the old days, but are still applicable today.
AIRSPEED, as the name implies, tells ATC how fast your airplane is
going through the air.
TIME ENROUTE tells ATC when to expect you at your destination.

One of the regs says that you have to advice ATC of any airspeed
deviations of +/- 10% (someone correct me if I am wrong, I do not have
the AIM in front of me).
However, the TIME ENROUTE should take into account headwinds and/or
tailwinds. This is important in the event of loss of comm.

Here is the question:
When you fill in the AIRSPEED box, do you give the actual indicated
airspeed for your cruise power setting?
Or, do you use the "groundspeed", based on winds aloft?

If you use the actual indicated airspeed, the math is not correct for
the time enroute.

If you use the actual airspeed and the calculated no-wind time enroute,
you mess up the system in the event of loss of comm, since you will not
be where they expect you in the elapsed time.

Further, in these days of RADAR, LORAN and GPS, do you advice ATC of
the groundspeed deviation from the airspeed?

From the AIM: "Block 4: Enter your true airspeed (TAS)"

Don't sweat the details.

Bob Gardner

"EDR" wrote in message
...

When filling IFR, there are two boxes you put numbers in, AIRSPEED and
TIME ENROUTE.

These go back to the old days, but are still applicable today.
AIRSPEED, as the name implies, tells ATC how fast your airplane is
going through the air.
TIME ENROUTE tells ATC when to expect you at your destination.

One of the regs says that you have to advice ATC of any airspeed
deviations of +/- 10% (someone correct me if I am wrong, I do not have
the AIM in front of me).
However, the TIME ENROUTE should take into account headwinds and/or
tailwinds. This is important in the event of loss of comm.

Here is the question:
When you fill in the AIRSPEED box, do you give the actual indicated
airspeed for your cruise power setting?
Or, do you use the "groundspeed", based on winds aloft?

If you use the actual indicated airspeed, the math is not correct for
the time enroute.

If you use the actual airspeed and the calculated no-wind time enroute,
you mess up the system in the event of loss of comm, since you will not
be where they expect you in the elapsed time.

Further, in these days of RADAR, LORAN and GPS, do you advice ATC of
the groundspeed deviation from the airspeed?

TAS.
I always tell myself they need to know it for spaceing me between the big
boys.... just so I don't run them over. )
--
Jim Burns III

Remove "nospam" to reply

In a previous article, EDR said:
Here is the question:
When you fill in the AIRSPEED box, do you give the actual indicated
airspeed for your cruise power setting?
Or, do you use the "groundspeed", based on winds aloft?

If you use the actual indicated airspeed, the math is not correct for
the time enroute.

They don't want the AIRSPEED so they can check your math, they want it for
separation purposes.


--
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reach. Its magic -- its power -- is based on the very real human connections
that form 'round its threads of conversation... the relationships that are
kindled, flamed and, on occasion, extinguished and mourned." -deCadmus

EDR wrote

Gee...EDR, you really disappoint me. :-)

One of the regs says that you have to advice ATC of any airspeed
deviations of +/- 10% (someone correct me if I am wrong,

Well, you asked for it! Advice is a noun. The word that you wanted
to use is advise, the verb.

When you fill in the AIRSPEED box, do you give the actual indicated
airspeed for your cruise power setting?

Nope! You use TAS, which is CAS corrected for pressure altitude and
temperature. Hmmm....how do you get from IAS to CAS???? :-)

If you use the actual indicated airspeed, the math is not correct for
the time enroute.

Of course, if you are using indicated airspeed, the math isn't correct
anyway.

If you use the actual airspeed and the calculated no-wind time enroute,
you mess up the system in the event of loss of comm, since you will not
be where they expect you in the elapsed time.

If you have "advised" ATC of a change in TAS, they recompute your ETA.


Further, in these days of RADAR, LORAN and GPS, do you advice ATC of
the groundspeed deviation from the airspeed?

EDR....you really aren't a pilot are you?

Bob Moore
ATP CFI

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.

Paul Tomblin wrote:


They don't want the AIRSPEED so they can check your math, they want it for
separation purposes.

That's what they tell you. If you lose comm but your transponder still
works life is golden for the controller. Lose the transponder too and
we'll use primary radar, although that makes the workload for the
controller go up significantly. Lose radar and ATC will essentially
clear a route for you. But no way, no how will the controllers call
AFSS, get your filed airspeed and/or ETE and simply wait for that time
to pass before resuming normal operations. Normal ops will not commence
until we know where you are.

Robert Moore wrote:
Gee...EDR, you really disappoint me. :-)

Stuff happens!

One of the regs says that you have to advice ATC of any airspeed
deviations of +/- 10% (someone correct me if I am wrong,

Well, you asked for it! Advice is a noun. The word that you wanted
to use is advise, the verb.

I knew that! I didn't catch it, but I see the online service did.

When you fill in the AIRSPEED box, do you give the actual indicated
airspeed for your cruise power setting?

Nope! You use TAS, which is CAS corrected for pressure altitude and
temperature. Hmmm....how do you get from IAS to CAS???? :-)

Nice catch! All these years I never noticed it was TRUE airspeed in
block 4. I have always used indicated. Oh well, that's what the whiz
wheel is for, isn't it?

EDR....you really aren't a pilot are you?

I prefer to think of myself as an "aviator". I chalk it up to a 15 year
layoff of IFR flying. 1200 hours, 400 in a 1945 Champ, doesn't give me
much practice.

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

"Newps" wrote in message
news:aqnLb.1278$na.1288@attbi_s04...


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.

Probably the only person who will care if you don't announce it is the DE on
your instrument checkride. And I don't think they will care very much. (I
did it on my checkride because I slowed to Va (not Vb) for turbulence).

-- David Brooks