MDA

[Jeffrey L. Whitaker]

Greetings, Can we input the MDA(H) somewhere for non-precision approaches? I'm either missing it, or the 73 does not allow. I'd love to hear what you guys have to say on this. JW

[Jeffrey L. Whitaker]

Jason, Thanks for the response. DH is a good option when the MDA(H) is reasonable. However, sometimes the MDA(H) is greater than 2K+. Just curious if there is a way to set MDA(H) for these non-precision approaches. From everything I can see the DH is the only option for setting MDA(H) on the 73's. If I'm wrong i'd love to be corrected. JW

[trisager]

Use the MINS knob on the EFIS control panel. Outer selector to BARO, inner selector sets MDA. Outer selector to RADIO, inner selector sets DH. Or am I misunderstanding your question?

[rocketfs]

Why not just the DH ?Afterall the height of the airport/runway is all that really matters.

Beacuse MDA is for non-precision approaches, a published DH is not available. Bert Van Bulck

Greetings, Can we input the MDA(H) somewhere for non-precision approaches? I'm either missing it, or the 73 does not allow. I'd love to hear what you guys have to say on this. JW

Do you mean in the FMC or as your minimums? Bert Van Bulck

[Jeffrey L. Whitaker]

Tom and Bert, Thanks for your responses. Tom, The MINS is used fro setting DH (precision approach). You have the option of selecting DH based on radio altemeter (RADIO) or pressure (BARO). Bert, Exaclty. I know in the MD-11 we could set MDA(H) through the MCDU after selecting a non-precision approach, e.g., RNAV, LLZ, LDA, etc. However, I do not see that the 73 has that ability. Am I incorrect? JW

[trisager]

The MINS is used fro setting DH (precision approach). You have the option of selecting DH based on radio altemeter (RADIO) or pressure (BARO).

No, DH is always based off the radio altimeter. You use it on Cat II and Cat III approaches. Standard ILS and non-precision approaches are based on barometric minimums. You set both the way I described.

[Guest Lawyer+Pilot]

Tom and Bert, Thanks for your responses. Tom, The MINS is used fro setting DH (precision approach). You have the option of selecting DH based on radio altemeter (RADIO) or pressure (BARO). Bert, Exaclty. I know in the MD-11 we could set MDA(H) through the MCDU after selecting a non-precision approach, e.g., RNAV, LLZ, LDA, etc. However, I do not see that the 73 has that ability. Am I incorrect? JW

The waypoint coinciding with the start of the MDA portion of the approach plan is listed on the legs page. The altitude restriction should already be there. If it's not, just enter it manually.

[SetSpeed]

I use baro knob for all non ils approaches and for cat 1 ils approaches. I find it a pain to use at the higher elevation airports. I hope there is a fast slew option with the service pack.

[rocketfs]

Tom and Bert, Thanks for your responses. Tom, The MINS is used fro setting DH (precision approach). You have the option of selecting DH based on radio altemeter (RADIO) or pressure (BARO). Bert, Exaclty. I know in the MD-11 we could set MDA(H) through the MCDU after selecting a non-precision approach, e.g., RNAV, LLZ, LDA, etc. However, I do not see that the 73 has that ability. Am I incorrect? JW

But a minimum is a mimimum, no? Wheter it's for precision or non-precision approaches, you can set it... Bert Van Bulck

[rocketfs]

No, DH is always based off the radio altimeter. You use it on Cat II and Cat III approaches. Standard ILS and non-precision approaches are based on barometric minimums. You set both the way I described.

ILS cat I also has a DH and uses barometric altitude measurement, no? Bert Van Bulck

[Jeffrey L. Whitaker]

Tom, I follow your point regarding the use of RADIO ALT for DA(H) on precision approaches. I am curious if the CDU allows for the input of MDA(H) for non-precision approaches. JW

[Chrjs]

ILS cat I also has a DH and uses barometric altitude measurement, no? Bert Van Bulck

As far as I know (please correct mei f i'm wrong) MDA = barometric altitude (cat I and above)DH = radio altimerte (cat II and III)

[trisager]

ILS cat I also has a DH and uses barometric altitude measurement, no?

On an ILS plate you will typically see something like DA(H) 298' (200). The first number is the decision altitude that you should set as your procedure minimum. The second number is the height above terrain (so you can infer that the terrain is 98' at that point). The procedure minimum that you should be using on a standard ILS is DA, not DH.

Tom,I am curious if we can input a MDA(H) for non-precision approaches (like those above) in the CDU.

No, on the 737 you do not enter the MDA for a non-precision approach in the CDU. You simply dial it in using the MINS selector in the BARO setting.

[Guest Lawyer+Pilot]

As far as I know (please correct mei f i'm wrong) MDA = barometric altitude (cat I and above)DH = radio altimerte (cat II and III)

Sort of. Decision Height (DH) and Altitude (DA) are for precision approaches. You must have a radar altimeter to use DH.MDA is used for non-precision approaches.

[Jeffrey L. Whitaker]

Tom, Excellent! Thanks for your response- I think it finally makes sense. I'm finding quite a bit of information as I research various SOP's on the topic. Not so much use during the approach phase, but how it is used during the peparture phase and even at times during cruise, e.g., the MSA for a particular segment in case of emergency descent. Again, thanks for the repsonses! JW