descent below minimums part 2

I appreciate eveyone's input. I sense that there is no clearcut answer.
The stepdown minimums are obviously there for a reason. On the other
hand, one would be allowed to fly a descent path of one owns choosing
when a visual approach clearance is issued.

The controller is often not aware if one is flying in IMC or VMC. What
is one to do on a approach when you have stepped down into VMC
conditions and the controller yells out an altitude and terrain alert?

Depends...

If you are on a visual approach, tell him "terrain in sight, but thank
you for asking."

If you are on a published (non-visual) IFR approach (IMC or VMC),
and...
(1) you are in IMC, and below the MDA or step down, get above the
published altitude immediately.
(2) try reducing your descent rate as you approach the MDA or step
down alt; ie go to 500 fpm for the last 300ft. You will set off few if
any terrain alerts that way, as opposed to driving right down at 1000
fpm and then levelling off in the last 100ft.

Make sure you do not descend out of the MDA towards a landing, even
with the ry in sight, unless you have reached the VDP if one is
published, or reached your own (calculated) VDP if one is not
published.

Calculate your own VDP as follows:
Take the HAT, and divide by 10. ie, if HAT = 400, HAT/10 = 40
Set the time from the FAF to the MAP into your timer, such that it
will count down to and reach 0 at the MAP.
Your VDP is when the timer shows HAT/10 seconds left. ie, HAT = 400,
HAT/10 = 40; do NOT descend out of the MDA until the timer reads :40 or
less.

Gene
CFII, MEI, ASC

If you are on a published (non-visual) IFR approach (IMC or VMC),
and...
(1) you are in IMC, and below the MDA or step down, get above the
published altitude immediately.

What if you are now in VMC on a stepdown fix and below the published
minimum for that stepdown, prior to the FAF?

OK... 1st, stepdown fixes are after the FAF... they are between the FAF
and the MAP.

The only IFR altitude that your are allowed to go below on an IFR
flight plan is the MDA or DA, and then only after you have the three
requirements satisfied as specd in FAR 91.175.

There is no provision for going below a step-down fix under an IFR
flight plan... VMC or IMC.

Gene

On 5 Jan 2005 19:26:45 -0800, wrote:

OK... 1st, stepdown fixes are after the FAF... they are between the FAF
and the MAP.

The only IFR altitude that your are allowed to go below on an IFR
flight plan is the MDA or DA, and then only after you have the three
requirements satisfied as specd in FAR 91.175.

There is no provision for going below a step-down fix under an IFR
flight plan... VMC or IMC.

IE, You can not go below a segment minimum altitude unless it is the
final segment and the criteria are met, OR you have come out into VMC
and cancel IFR.

I heard this very scenario on MBS approach last night.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Gene

what is MBS approach and please quote me the FAR this opinion is based
upon

On 4 Jan 2005 23:15:59 -0800, wrote:

Make sure you do not descend out of the MDA towards a landing, even
with the ry in sight, unless you have reached the VDP if one is
published, or reached your own (calculated) VDP if one is not
published.

Calculate your own VDP as follows:
Take the HAT, and divide by 10. ie, if HAT = 400, HAT/10 = 40
Set the time from the FAF to the MAP into your timer, such that it
will count down to and reach 0 at the MAP.
Your VDP is when the timer shows HAT/10 seconds left. ie, HAT = 400,
HAT/10 = 40; do NOT descend out of the MDA until the timer reads :40 or
less.


Remember that the headwind component to be included in this
calculation for groundspeed is the cosine of the wind angle
multiplied by the velocity of the wind in knots, (multiplied by
5280/6200 if you are measuring your airspeed in MPH).

On 4 Jan 2005 22:56:49 -0800, "hsm" wrote:

I appreciate eveyone's input. I sense that there is no clearcut answer.
The stepdown minimums are obviously there for a reason. On the other
hand, one would be allowed to fly a descent path of one owns choosing
when a visual approach clearance is issued.

The controller is often not aware if one is flying in IMC or VMC. What
is one to do on a approach when you have stepped down into VMC
conditions and the controller yells out an altitude and terrain alert?

Say "Roger"


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

On 4 Jan 2005 22:56:49 -0800, "hsm" wrote:

I appreciate eveyone's input. I sense that there is no clearcut answer.
The stepdown minimums are obviously there for a reason. On the other
hand, one would be allowed to fly a descent path of one owns choosing
when a visual approach clearance is issued.

The controller is often not aware if one is flying in IMC or VMC. What
is one to do on a approach when you have stepped down into VMC
conditions and the controller yells out an altitude and terrain alert?

If you are legally below the charted altitude, which means you have the
runway in sight and are making a normal approach, then I would say "Roger"
(after double checking to be sure that everything was OK).

But I've gotten low altitude alerts on occasion even when on a glide path
(needles centered). I am told you can also trigger the alert by descending
more rapidly than the computer thinks you should (on a non-precision
approach) -- this may be OK for a transport category jet aircraft, and not
necessarily applicable to a small Part 91 CAT A a/c.



Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

On Wed, 05 Jan 2005 08:12:39 -0500, Ron Rosenfeld
wrote:

But I've gotten low altitude alerts on occasion even when on a glide path
(needles centered). I am told you can also trigger the alert by descending
more rapidly than the computer thinks you should (on a non-precision
approach) -- this may be OK for a transport category jet aircraft, and not
necessarily applicable to a small Part 91 CAT A a/c.



Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)


True. Often with approaches where the nav facility is on the field
and there is no FAF. You can get to minimums pretty far out and
usually set off the computer alarms.