NDB (BN) RWY 15 IFR approach at Basle Mulhouse LFSB

[manucordier]

Hi,

Could someone shed some light on the Basle Mulhouse LFSB - NDB BN RWY 15 IFR approach (http://www.cours-de-math.eu/ifr-training/Bale-Mulhouse-NDB-BN-Rwy-15.jpg) ?

You will find here the IFR plate I am talking about :

http://www.cours-de-math.eu/ifr-training/Bale-Mulhouse-NDB-BN-Rwy-15.jpg

To summarize, after a missed approach you have to enter a non standard hold overhead BN NDB at 4300 ft according to the french AIP online.

Outbound leg in the hold:

However something is not clear in y mind : should I make an outbound leg of 1 minute after I passed the abeam, or the end of the outbound leg is determined by the radial 017 from BN at DME 12 from CLR ?

Racetrack pattern :


Outbound leg :
Then when I am ready and cleared for approach, I should descend to 2800 ft after I passed the IAF (BN NDB) and enter now the racetrack pattern which has a 1min30 sec outbound leg unless I have a working DME, then I start the inbound turn at radial 017 from BN 12 DM from CLR. Is that right ?

FAF :
And without DME, the FAF will be situated at 1min30 second after the inbound turn is completed. Is that right ? (But then I'll have a problem because my FAF will be overhead BN NDB and I'll be 1000 feet too high !?)

Any other idea about that ?

Thanks.

[Northbeach]

To summarize, after a missed approach you have to enter a non standard hold overhead BN NDB at 4300 ft according to the french AIP online.


RE: LFSB/MLH NDB Rwy 15 Basle-Mulhouse, France

During the missed approach there are a number of steps to accomplish per the instructions; provided you comply with them and when above 3800' you turn right direct to BN and hold as published at 4300'. It is a left hand pattern, so by definition that is a non-standard hold.


Outbound leg in the hold:

However something is not clear in y mind : should I make an outbound leg of 1 minute after I passed the abeam, or the end of the outbound leg is determined by the radial 017 from BN at DME 12 from CLR ?



Depends if you are passing time in a holding pattern or whether you are cleared for the approach and commencing your turn towards the FAF. If you are holding then begin turning inbound after 1 minute passing abeam BN outbound at your holding altitude of 4,300'.


Racetrack pattern :


Outbound leg :
Then when I am ready and cleared for approach, I should descend to 2800 ft after I passed the IAF Yes (BN NDB) and enter now the racetrack pattern which has a 1min30 sec outbound leg unless I have a working DME, then I start the inbound turn at radial 017 from BN 12 DM from CLR. Is that right ?



I would say that you are would "start the inbound turn" at the 197 bearing to BN NDB. BN is a Non-Directional Beacon it doesn't have "radials" it can't as it is non-directional. But I understand what you meant we are talking about the same point in space (or the 12.0 DME from CLR TAC (110.0 & not shown on the chart if it is available)


FAF :
And without DME, the FAF will be situated at 1min30 second after the inbound turn is completed. Is that right ? (But then I'll have a problem because my FAF will be overhead BN NDB and I'll be 1000 feet too high !?)



I identify the FAF as the maltese cross located at 3.1 NM 324 bearing from/154 bearing to BN NDB. If CLR TAC is operational the FAF may also be identified as the D13.5 CLR while on the 154 bearing to BN NDB.

Being cleared for the approach on the inbound leg 154 bearing to BN, having descended to 2,800 and having TAC DME available once passing the 13.5 DME from CLR you begin your descent to cross the BN at 1850' and continue down to 1340'.

If we stay at 2,800' until passing BN there is no possible way to get down to 1340' in 2 NM and be stable (1,460' to lose). At 476' HAT one would need to see the runway at approximately 1 1/2 miles for a stable continuous descent [I am thinking in terms of the small and slow Boeing 737 I fly].

Without the DME I still have my known ground speed. If my ground speed is 140 knots and the FAF is 3.1 NM from BN NDB I am going to start my descent 1:32 seconds from my BN NDB estimate once I am established inbound on the 154 bearing to BN NDB.

I am not absolutely positive here** but I think if you begin your inbound turn once you pass the 197 bearing to BN on the outbound leg and your groundspeed is greater than 150 kts at 1 minute and 30 seconds after initiating your inbound turn and established on the 154 bearing to BN you may commence your descent to cross BN NDB at 1,850' and continue down to a DA/MDA (H) of 1,340. This is how I would apply the HIPPODOME/RACETRACK note in the upper left hand corner of the main view of the approach chart.

The approach is named NDB BN RWY 15 therefore DME from CLR TAC is not required. If it is available use it by all means use it to positively identify the FAF of D13.5 CLR TAC, but CLR TAC is not required for this approach.

There is also a note that this approach is to be used if the VOR/DME BLM is U/S unserviceable. If the BLM VOR DME is useable then use that approach in instead of this one.

This published approach would likely be my last choice for an instrument approach to this airport - but it makes an excellent test question.

**Because I am not absolutely positive I would make certain I spoke to my dispatcher, the training department, fleet captain or some company instructor pilot prior to accepting this approach into Basle-Mulhouse France.

I do not have all the answers and am always willing to learn,

[manucordier]

Thank you very much for that very complete answer.
After having flown (on my FS2004 - B737-500) that approach about 10 times this evening, I finally came to the same conclusions than you did. It makes a lot of sense.

Thanks again and good flights to you.