View Full Version : mdh/mda + 50ft for cat B aircraft
22nd Apr 2012, 11:53
i'd like to know if it's common procedure add 50ft to MDH/MDA for category B aircrafts operators(specially for turboprops)
Thanks for the answers.
Yep it's required for all CANPA approaches. I think some airlines use 30 for their smaller aircraft most however use 50.
If you don't use something you will bust your MDA. When you add the additive to it then it becomes a derived decision altititude DDA.
NO - not required under JAROPS IF an MDH is published and used. Only for MDA.
EDIT: SORRY - Mis-typed
Should read Ifa DH/DA is published.
22nd Apr 2012, 14:54
There is NO LEGAL REQUIREMENT.
HOWEVER... The operator must not sink below the MDA(H) on any Non precision approach.
Almost all European non precision approaches have now a DA iso. an MDA.
This however does not mean that you can go below the published DA minima. It depends on the issuer of your charts, but Jeppesen for example does NOT provide any blanket for go around loss of altitude at DA at a CANPA approach. It is up to the operator to decide which extra altitude to add to the published minima in order to avoid a bust.
There are some EASA members that require an extra altitude, for example, France requires that you add on Jeppesen CANPA approaches at least 40'.
In my company, we use 50ft. add-on to the published DA. We use Jeppesen.
With regard to the MDA it is a legal requirement for us... As it is in the Operational Manual as approved by the NAA.
We have to add 50 feet to any MDA, as it is not permissible to go below the MDA I don't see how you can assure you don't technically bust the regulation without an additive when performing a CANPA approach.
When the approach is designed (current me if I'm wrong) a DA has an allowance due to the fact a go around at DA will result in the aircraft dropping below the published altitude.
An MDA however, there is no factor built in.
22nd Apr 2012, 15:32
Please note that the 50' protection is applicable only in case of non precision approach flown as a continuous descent down to the runway!
If you fly a non precision approach with the MDA a few miles before the visual descent point, then adding the 50' has no effect, as the aircraft will nicely perform the level off at the MDA.
23rd Apr 2012, 03:33
Yeh I'm the same as quianor - I level off at MDA about a mile
before the VDP..which in some very tight cases can mean the
difference between getting in or diverting.
blah blah blah
23rd Apr 2012, 03:42
A NZ domestic operator has somehow managed to get the NZCAA to allow an MDA to be treated as a DA for CANPA approaches, with no addition to allow for sink. This means that MDA is busted, but as its only a little bust its ok apparently.
Interestingly the IR instructor guidelines make no allowance for this.
I need to dig out where I read it exactly (I forget as we don't do any) but I'm sure in EU land you are not allowed to fly a level segment at MDA on a NPA unless it is specifically authorized in your OM-C.
Edit: Found it in our OPS manual.
Not sure if it is only a company requirement.. But as a general rule we are not allowed to level off at the MDA it must be treated as a DA.
However... If you do fly a level segment don't forget you have to increase the required visibility as per:-
8.4.5 Approach Flown with a Level Flight Segment If the approach is flown with a level flight segment at or above MDA/H, 200m shall be added for CAT A and B aircraft and 400m for CAT C and D aircraft to the minimum RVR/CMV value
23rd Apr 2012, 05:48
It can be found in EU-OPS, Appendix 1 (new) to OPS 1.430. There are some exceptions though, but not many.
Anyway, "our" chart provider (LIDO) provides EU-OPS minima which means all non precision (except circling) minima have to be treated as DA. We simply fly that, CANPA to DA and then either land or go around.
2nd May 2012, 22:17
First of all,
Thanks everybody gave an answer.I use Lido toon,so i 'd like ask more details to DENTI on why we could fly a canpa approach down to mdh/mda and consiter it like a dh/da.still you are on a non precision app and is stated that you are not allowed to fly below mdh/mda without visual references and so on.i probably miss something i guess.i will check again on lido NAV section.
Just this last month... We got a crew notice that the CAA have now approved us to treat an MDA as a DA without any additive.
For years we have been adding 50' to it... Now it is no longer required. (for our company at least)
4th May 2012, 09:06
Thanks PT6A,could you just tell me on witch basis you are allowed to consider an mda/mdh like da/dh?is that valid for p-rnav approach?canpa?any eu-ops refrences?
Hamilton - extensive coverage on PPrune if you search for it. It is down to your regulatory authority to survey and assess an MDA/H as 'fit' to be used as a DA/H and then you can, on a CANP (CFDA) approach only. Otherwise you add xxx' or increase RVR as stated before - this is covered in Appendix 1 (New) to EUOPS 1.430 and an excellent explanation of the whole thing is on that previous thread. As always, Hamilton, your company Ops manual is your reference. In simple terms if it doesn't say you can you can't! - what does that say?
Here, with acknowledgement to Jepp, is what they say:
CDFA will be the Standard on Jeppesen charts
non-CDFA only in exceptional cases
Jeppesen will publish DA(H) instead of MDA(H) for CDFA approaches
Jeppesen will not use an add-on when publishing a DA(H),
to use or not use an add-on is still the operators responsibility
Jeppesen will publish MDA(H) for non-CDFA approaches
PS This has to be one of the most muddled changes I have seen for years.