Modesto2 From United States of America, joined Jul 2000, 2876 posts, RR: 5 Posted (14 years 9 months 4 weeks ago) and read 1034 times:
There is a point at each flight (specified on the flight plan) marked "BGN Descent". At this point, the aircraft should commence its descent. However, how often does the air traffic controller clear the aircraft to a lower altitude in accordance with the flight plan? In other words, do air traffic controllers descend aircraft as specified on the flight plan or do they usually do it a few miles/minutes earlier or later? And I'd like to hear any unique stories from the airline pilots about being cleared too early or too late! As always...thanks for the help!
Jetpilot500 From United States of America, joined Nov 2000, 78 posts, RR: 0
Reply 1, posted (14 years 9 months 3 weeks 6 days 20 hours ago) and read 1006 times:
This is only on the flight plan for fuel planning purposes. ATC does not see this on the thier flight strip, so they do not know when you arrive at this point. Controllers have a pretty good idea of when to start an aircrafts decent, but sometimes you need to remind them. Many corporate jets fly higher than the airlines, requiring them to start the decent earlier because they are higher, so we often need to remind them when we need to start down.
Joe_R From , joined Dec 1969, posts, RR:
Reply 2, posted (14 years 9 months 3 weeks 6 days ago) and read 992 times:
"I'd like to hear any unique stories from the airline pilots about being cleared too early or too late!"
ATC's job is to keep airplanes from hitting each
other... they'll decend a flight based on that
premise and when "possible" on the needs of
Early isn't usually too much trouble unless you
are tight on fuel, because your fuel flow is higher
at lower altitudes. Sometimes an early descent
is requested to get a smoother ride.
Late is usually a problem, it's all about energy
and comfort. Obviously you gotta get down to
airport elevation in order to land, so you can
either use an aggressive (uncomfortable)
descent or simply lengthen the distance to
By aggressive I mean - engines at idle, spoilers
out, nose way down, passengers feeling their
seatbelts - kinda thing.
To lengthen your distance, you just need to
fly though more air, turn out, S turns, anything
but direct to the airport. This wastes time, and
if it makes you late - you become unpopular!
Different areas and some specific airports have
consistant problems that frequently cause a
late descent. More often than not, it cannot
If you take the Northeast for example, you have
the case in point...
Many, many airports close together, very
complicated airspace, and tons of traffic of
all levels of performance.
Too often, the "late descent" and crossing
restriction are such that it exceeds the abilitites
of the aircraft or tolerance of the passengers,
so we get backed into a corner of sorts.
Careful coordination with ATC is the only way
out, typically - the crew relays "what" they "can"
do - and ATC responds with what they "must"
have... eventually a solution that works for
both is arrived at, and everything works out.
So... if we do our jobs right, the passengers
are comfortable and still arrive on schedule.