[jhb_airlines] Re: No speed restriction

  • From: "Bones" <bones@xxxxxxx>
  • To: <jhb_airlines@xxxxxxxxxxxxx>
  • Date: Wed, 21 Sep 2005 14:49:38 +0100

Just realised that there is a missing line in the last paragraph. This
should read:

In the descent the process is reversed. The pilot will fly at Mach .76 until
the IAS reaches 290 knots, which should occur around FL290. During this part
of the descent the aircraft will accelerate slightly from 245 to 290 knots
IAS (435 to 445 Kt TAS). In the descent from FL290 to FL100 the aircraft
will be flown at a constant 290 knots IAS and the TAS will decrease from 445
to 334 knots. At FL100 speed is further reduced to 250 knots IAS (289 Kt
TAS/Mach .45). IAS will then be reduced to around 210 knots in preparation
for configuring the aircraft for approach."

As FPI gets busier (or if you try VATSIM when it's busy) you will find that
speed control gets more critical. ATC cannot take a stream of traffic into
an airport with really nice spacing if one aircraft is going substantially
faster than the rest. We tend to ignore speed (a bit) for the moment but
traffic density - as in real life - is going to force more strict procedures
on everyone.

bones



-----Original Message-----
From: jhb_airlines-bounce@xxxxxxxxxxxxx
[mailto:jhb_airlines-bounce@xxxxxxxxxxxxx] On Behalf Of Bones
Sent: 21 September 2005 14:31
To: jhb_airlines@xxxxxxxxxxxxx
Subject: [jhb_airlines] Re: No speed restriction


Speed restriction on most SID's is 250kts so I'd be interested if you have
found any that specify anything slower.

When I give a no speed restriction instruction to pilots I mean that you can
exceed the 250kt limit below FL100. Most jets these days use a 290/300kt
climb speed up to the point where it hits M0.76 and then fly a Mach climb
after so 250kts up to FL100 is a bit restricting.

If it helps here is a snippet from a Speed Control document I have:

"Looking at a typical climb/descent profile for an MD80 the following can be
observed. The aircraft climbs at 290 knots IAS until it reaches Mach .76. It
continues the climb maintaining .76 to cruise altitude, cruises at .76 and
holds that Mach speed in descent until reaching 290 knots IAS again. As
there is a speed limitation of 250 knots IAS below FL100 the initial climb
will be at 250 knots IAS (289 Kt TAS/Mach .45). The aircraft will then
accelerate to 290 knots IAS (334 Kt TAS/Mach .52 at 10,000 feet) and then
climb at this constant indicated speed.

During this climb both the TAS and Mach number will be increasing as
follows:

                TAS             Mach
15,000  359kt   .57
20,000  387kt   .63
25,000  418kt   .69
29,000  445kt   .75**
33,000  441kt   .76 (268 kt IAS)
37,000  435kt   .76 (245 kt IAS)
** From this point on the pilot will fly at Mach .76 and no longer use IAS
as a reference unless requested to do so by ATC.

If the crew had not changed from IAS to Mach number and tried to hold 290
knots IAS all the way to FL370, the speed at top of climb would be Mach .88
? far in excess of the permitted limit.

In the descent the process is reversed. The pilot will fly at Mach .76 until
the IAS reaches 290 knots, which should occur around FL290. During this part
of the descent the aircraft will accelerate slightly from 245 to 290 knots
IAS (435 to 445 Kt TAS). In the descent from FL290 to FL100 the aircraft
will be flown at a constant 290 knots IAS and the TAS will decrease from 445
to 334 knots. IAS will then be reduced to around 210 knots in preparation
for configuring the aircraft for approach.

bones

-----Original Message-----
From: jhb_airlines-bounce@xxxxxxxxxxxxx
[mailto:jhb_airlines-bounce@xxxxxxxxxxxxx] On Behalf Of Phil Reynolds
Sent: 21 September 2005 12:35
To: JHB
Subject: [jhb_airlines] No speed restriction


Hi Bones,

Another ATC query.  In my last online session I departed on a specific SID
with an initial altitude of 4000ft given. Once contacting the APP controller
he advised to climb to FL120, no speed restiction.  Does the no speed
restiction just overrule any SID speed restictions or does this instruction
also overrule the 250kts below 10000ft (in the UK) rule?

Cheers

Phil






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