PDA

View Full Version : Loc (GS Out) Appr - MDA / Missed Approach Point


extricate
10th Jun 2018, 09:36
Hi,

Can I confirm at which point we go around in the event of no visuals is either the MDA or the Missed approach point as stipulated in the chart whichever comes first?

Thanks

parkfell
10th Jun 2018, 10:00
Why don't you ask your Instructor, or better still look in your study books.

If you use the technique of MDA/H, then you descent to it +50ft, and G/A no later than the MAPt if not visual.
If you descend to a DA/H, you G/A at that point, but no later than the MAPt.

From the THREAT AND ERROR consideration, levelling at MDA +50ft is regarded as more risky especially the heavier the ac.
DA/H technique is a safer and cleaner way to operate.
Non FAA rules....

Chesty Morgan
10th Jun 2018, 11:43
Surely nobody does the dive and drive anymore. Is it even still taught?

As Parkfell said go around when you reach whichever minima youíre using.

Check Airman
10th Jun 2018, 13:31
There are airlines in the US still doing dive and drive. The above information is also incorrect under FAA rules.

FlightDetent
10th Jun 2018, 14:04
There is no such thing as DA for 2D or even NPA approaches. It is MDA.
- maybe you want not to continue to MAPt after reaching it
- maybe you are required by regulation to "treat is as DA" and execute the MISAP without delay
- maybe you want to add a small buffer such as 50' on top, to make sure you do not go under.
But it still is MDA. No matter Jeppesen decided to print "DA" on their commercial product.

The items above are irrelevant if you just need to fly it. OTOH, when seeking understanding, sticking to the definitions would be prudent.

Based on ICAO Doc 8168 PANS-OPS.
https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_120-108.pdf

BizJetJock
10th Jun 2018, 18:42
But it still is MDA. No matter Jeppesen decided to print "DA" on their commercial product.

Er...no. Jeppesen only print "DA" if the state have published a DA rather than MDA. You may want to catch up with the last ten years sometime.

FlightDetent
10th Jun 2018, 22:46
BJJ: States do not publish DA/H or MDA/Hs, save for few that insist on having State Minima. Only OCA/H.

When CDFA and immediate G/A upon reaching MDA - no level flight towards MAPt permitted (treat it as a DA), were mandated by EASA, Jeppesen did exactly as I wrote, probably responding to a strong if not somewhat confused customer demand.

Never mind the good intentions, and FAA A/C 120-108 crystal explanation almost 7 years ago (see the A/C linked above, 6 (f) Derived Decision Altitude), that "DA" on Jepp NPA plates still confuses many.

I'll show you mine:

aterpster
11th Jun 2018, 01:44
Er...no. Jeppesen only print "DA" if the state have published a DA rather than MDA. You may want to catch up with the last ten years sometime.
As I recall this is only EASA. Correct?

FlightDetent
11th Jun 2018, 02:37
As I recall this is only EASA. Correct? Not correct, and not EASA related the way it's written.

BTW maybe you could post LGSK LOC 20 and EBBR VOR 07L from Jepp? Just for comparison, the minima box would do. Thanks.

aterpster
11th Jun 2018, 14:21
Not correct, and not EASA related the way it's written.

BTW maybe you could post LGSK LOC 20 and EBBR VOR 07L from Jepp? Just for comparison, the minima box would do. Thanks.

https://cimg9.ibsrv.net/gimg/www.gmforum.com-vbulletin/1000x303/loc20_b8df899be46d25bc39c30711c2b525cc500198b7.jpg
https://cimg1.ibsrv.net/gimg/www.gmforum.com-vbulletin/1000x297/vor7l_e293243d2dd3de8b3a50f9c7428a44bd62918b42.jpg

Tee Emm
11th Jun 2018, 15:02
Why don't you ask your Instructor,

Who often wouldn't have a clue anyway. Never take your instructors word - always go for verifiable facts - not personal opinions

Check Airman
11th Jun 2018, 15:08
Who often wouldn't have a clue anyway. Never take your instructors word - always go for verifiable facts - not personal opinions

Agreed. I'll add that if your instructor often doesn't have a clue, it may be time to get another.

pineteam
11th Jun 2018, 15:29
+2. Instructors should have solid knowledge but they are human and donít know everything and sometimes unconsciously tell untrue things. If I had learned something on how to improve my technical knowledge is that unless itís written black an white with reliable source, what you hear or read might be completely bull:mad:.

aterpster
11th Jun 2018, 16:29
Who often wouldn't have a clue anyway. Never take your instructors word - always go for verifiable facts - not personal opinions
A good instrument flight or ground instructor has verifiable references at hand.

FlightDetent
11th Jun 2018, 21:01
+3. It's unfortunate how commercial pressures (including self-funding) cut down the training time. 0 to ATPL in 1 year, speaking EU.

@aterpster thank you. It's nice they re-introduced the MDA/H label, it helps a lot.

I believe Jeppesen does only print one version of minima sheet per each approach chart, and that one is distributed worldwide (*). The label "STANDARD" stands for WX minima provided as per Amendment 1 (new) to (EU) OPS 1.430. While EU-OPS is no longer in force the values remain numerically identical to the current EU standard EASA IR. The one previous was "JAR-OPS" for us here. Or you could also have STATE or PANS-OPS based on different legislation, and I suspect there must be a table for FAA minima / US operators.

Now imagine e.g. Moscow some time ago, where the RF would provide STATE minima for local operators and mandate them (probably no longer the case). All the other countries operators would use PANS-OPS minima most likely, except for the EU guys. Half of those would use JAR-OPS during the transition period, the other half already STANDARD. As explained by the helpful Frankfurt Jepp people, it was a major headache to decide which customer group should take precedence as there could be only one single version of the chart.

I am clueless what are the Jepps options these days, admittedly. Some other charting providers, who started younger with a more digital back-office as well as significantly smaller business reach, would simply ask the customer: Which legislation = minima you operate to? And then provide the aerodrome charts with those printed for any place worldwide. And that is the spirit.

(*) unless you go for TAILORED charts, where the money starts flowing.

desertpilot2457
7th Jul 2018, 08:55
The FAA has not yet mandated constant rate descents, but they are likely to do so. It is mandatory in Europe and the approach charts include target altitudes at every mile on the final segment. The pilot is required to adjust the descent rate to cross each mile at the charted altitude. This should cause the aircraft to reach the MDA on profile. Although this may increase the workload, especially for single pilot operations it is designed to keep the pilot/crew aware of the aircraft altitude during the entire approach and reduce the possibility of descending below the MDA. . Another problem besides increased workload, is that you are not allowed to descend below the MDA, so the missed approach should be started 30 ft prior. There are varying degrees of dive and drive and i am not a proponent for cutting the power to idle and descending like a rock. Until the FAA mandates the constant rate profile, I prefer to descend at a reasonable rate of 1000 ft/min or less,(depending on aircraft speed) and level off momentarily at the MDA, which gives a little more opportunity to find the runway in low visibility. It is especially necessary for circling approaches. Nothing replaces a good scan which includes altitude, airspeed, course and heading control, and neither should be more emphasized than the other. I fear this new mandate may cause more airspeed and course deviations. Call me old school, but old school works best for me. Aircraft capable of conducting LNAV/VNAV approaches use a vertical glide path (VGP) on non precision approaches and are required to use a derived decision altitude.usually 30 feet above the MDA

oggers
8th Jul 2018, 09:29
Hi,

Can I confirm at which point we go around in the event of no visuals is either the MDA or the Missed approach point as stipulated in the chart whichever comes first?

Thanks

You go around not later than the MAP. You turn not earlier than the MAP. You descend not lower than MDA. For a dive and drive NPA, if not visual at MDA you may continue to MAP or go around.

If using CDFA your minima becomes a DA (or DDA or whatever terminology is in use in your operation) and DA and MAP are nominally the same point. Therefore you may dip below minima but the decision and action has already been taken to go around. An equivalent or greater level of safety has been achieved because you are at a known point along the final approach as opposed to reaching minima at no particular point along the final segment.

FlightDetent
8th Jul 2018, 13:55
oggers: short and precise at the same time, hats off!:ok:

pineteam
9th Jul 2018, 08:30
If using CDFA your minima becomes a DA (or DDA or whatever terminology is in use in your operation) and DA and MAP are nominally the same point. Therefore you may dip below minima but the decision and action has already been taken to go around.

Interesting. In our company we must go around at 100 above minimum if not visual so I assumed it was always a MDA while doing a NPA regardless of doing a CFDA or 'Dive and Drive' technique. . It's a fail item in the sim if we go below the minimum. I guess it's only a company or aviation authority restriction.

underfire
9th Jul 2018, 16:31
FAA land...
LPV -DA
RNP - DA
LNAV/VNAV - DA
LNAV - MDA

Interesting. In our company we must go around at 100 above minimum if not visual so I assumed it was always a MDA while doing a NPA regardless of doing a CFDA or 'Dive and Drive' technique.

That is because the criteria uses a 50 foot momentary descent on a DA...for most ac, that is not adequate if GA at the DA.

Use of Decision Altitude (Height) in Continuous Descent Final Approaches (https://www.skybrary.aero/index.php/Use_of_Decision_Altitude_(Height)_in_Continuous_Descent_Fina l_Approaches)

FlightDetent
11th Jul 2018, 20:03
Reader beware. That Skybrary link points to a re-hash of Jeppesen's own explanatory leaflet, which was put together at very early stages of their understanding. And it is quoted out of context.

With all due respect to Skybrary's mission, dedication and results (3x thumbs up) they are still de facto a blog, no relevant authority.