Can you descend below DH or MDA??

[pgcfii2002]

I was reading the requirements for descending lower than the DH and MDA, am I correct to assume you must have:

1) Stabilized approach
2) Runway enviornment in sight
3) Visibility greater than published for the approach

Correct me if I am wrong........

 

[Papps]

I believe published MDAs and DHs are not applicable as long as you "really really don't feel like going missed".

 

[nosehair]

3) Visibility greater than published for the approach

Correct me if I am wrong........

"visibility not less than published..."

 

[neflier]

I was reading the requirements for descending lower than the DH and MDA, am I correct to assume you must have:

1) Stabilized approach
2) Runway enviornment in sight
3) Visibility greater than published for the approach

Correct me if I am wrong........

Actually, you can descend below DH, but not continue below DH. DH is the altitude where a decision is made, continue the approach, or execute a missed. Assuming a 100 kt GS, you have a descent rate of roughly 500 fpm. A decision to go missed at 200’, with a descent rate of 500 fpm will result in the aircraft being below 200’ during the initial part of the missed. Perfectly legal.

No don’t ask what happens if the runway environment comes into sight during the dip below DH. A decision to go missed has already been made and the aircraft is no longer stabilized on the approach. Continue with the missed.

 

[nosehair]

Actually, you can descend below DH, but not continue below DH. A decision to go missed at 200’, with a descent rate of 500 fpm will result in the aircraft being below 200’ during the initial part of the missed. Perfectly legal.

.....(waiting)....3....2....1...

 

[Papps]

.....(waiting)....3....2....1...

Waiting for what, thats correct info. Unless you pull 9 g's at DH you are going below it a few feet. At DH you make the decision to continue based on what you see or go missed.

 

[Amish RakeFight]

Papps is right.

 

[nosehair]

Waiting for what

for what I though might be some flak on that one. I haven't seen that "hashed out" on any of these boards lately...thought there might be some newbies who haven't heard it before, or some oldies (like me) who prefer to read the word "continue" as in "going below DH"...but that's just me. I'm not gonna argue about it, you see it one way, which is plausible, I see it another way, which makes me feel a little safer.

I was waiting on some other viewpoints.

 

[Papps]

yeah this one has confused people forever. If your in jet doing 140 knots on final and 700-800 fpm to hold glide slope. The pilot not flying will call "minimums no runway" right at DH. In the rj you will say hit the TOGA button push the levers up and say "go around go around thrust flaps 8" and pitch up to the Flight director. The plane will be below DH by the time you start uphill again. And no check airman on earth will fail you for that.

 

[A Squared]

for what I though might be some flak on that one. I haven't seen that "hashed out" on any of these boards lately...thought there might be some newbies who haven't heard it before, or some oldies (like me) who prefer to read the word "continue" as in "going below DH"...but that's just me. I'm not gonna argue about it, you see it one way, which is plausible, I see it another way, which makes me feel a little safer.

I was waiting on some other viewpoints.

Well, you're being pretty vague and non-committal here, but reading between the lines, it *appears* that you are advocating beginning a missed approach so as not to go below the Decision Altitude (DA).

If that is not your position, disregard. If that is your position, you are incorrect. By all means, operate how you feel comfortable, heck, add 300 feet to all the MDA's if you like to, but that is certainly *not* how a DA is intended to be used. The name says it all:

DECISION Altitude

It is the altitude at which you make the decision to continue or to go missed. It isn't just some silly meaningless words that were accidentally chosen because they looked cool on the approach plate. Just like "minimum descent altitude means the lowest you are allowed to go, decision altitude means that the altitude at which you decide to execute the missed approach. And of course, when you make the decision to go around at decision altitude, unless you have infinitely quick reflexes and an infinitely powerful airplane, you will go briefly below the DA as the airplane transitions from descent to climb. How much depends on the specifics of the airplane, but it will happen and the system is designed to operate that way.

Like I said, if you like to treat DA as a MDA, knock yourself out, but to say and teach that as the correct method is every bit as factually incorrect as teaching that one should never descend below 300' above the MDA on an non-precision approach.