FALA RNAV approach Rwy 07

RNAV, GNSS, GPSS. Your place to discuss all aspects pertaining to Instrument Flying.

Moderator: Moderators

User avatar
Hop Harrigan
Frequent AvComer
Posts: 954
Joined: Tue Jun 01, 2010 7:55 pm
Has liked: 0
Been liked: 6 times

FALA RNAV approach Rwy 07

Unread post by Hop Harrigan » Tue Jan 15, 2019 4:48 pm

Hi,
So I have a few queries on the above chart if some kind knowledgeable soul could help...(chart attached).
1) Approaching LA1N2 minimum alt is F090. However ATC usually route me “DCT LA1N2 descend to 8000’ QNH...”. Are they breaking their own minima here or are they helping a light aircraft which they know can’t handle the steep descent?
2) On the vertical profile, what is the significance of the ‘VNAV only’between the SDF and LA1MP? The stated alt of 5630’ On the profile at the SDF also doesn’t gel with the data in the straight in approach box at left bottom where ‘LNAV only’ is 5836 or 5224’ dependanton climb profile??
Many thanks,
Hop
15D5E29D-8EE6-4B8D-BC44-DCC25FB52EAC.png
You do not have the required permissions to view the files attached to this post.
There is no gravity...the Earth sucks
User avatar
tansg
Rolling
Posts: 171
Joined: Thu Mar 19, 2009 8:29 pm
Closest Airfield: OMAA
Has liked: 0
Been liked: 2 times

Re: FALA RNAV approach Rwy 07

Unread post by tansg » Thu Jan 17, 2019 10:44 am

As the guilty party who approved this procedure I will endeavour to answer your questions.

1) Approaching LA1N2 minimum alt is F090. However ATC usually route me “DCT LA1N2 descend to 8000’ QNH...”. Are they breaking their own minima here or are they helping a light aircraft which they know can’t handle the steep descent?

No they aren't. The F090 is for the aircraft to fly the constant descent approach of 3degrees from beginning to end. Nothe the TAA for that sector is 8400' and that the levels in the hold are F090 - 7700' (hard minimum = not below 7700' indicated the line under the 7700'). Furhter if you look at the ATC SURVEILLANCE MINIMUM ALTITUDE CHART you will see the minimum altitude for that sector is 8000'. So as long as you under positive Radar control they can route you down to 8000' via LA1N2.

2) On the vertical profile, what is the significance of the ‘VNAV only’between the SDF and LA1MP? The stated alt of 5630’ On the profile at the SDF also doesn’t gel with the data in the straight in approach box at left bottom where ‘LNAV only’ is 5836 or 5224’ dependanton climb profile??

SDF = Step Down Fix and so is only applicable for LNAV approach. The VNAV only on the vertical profile is to indicate that continuation of the approach to the lowest minima is for LNAV/VNAV ops only. As you rightly state the minima for LNAV only is 5836' if you can only maintain a 2.5% Missed Approach climb profile (an archaic ICAO requirement to cater for old piston engined airliners) and 5224' if you can maintain a 4.8% Missed Approach Climb Profile (easy for most modern commercial aircraft). Which is higher than the LNAV/VNAV minima of 5600' (2.5% climb) and 4860' (5% climb). Lanseria was pushing to get an "ILS-like" minima for this approach (remember they had no ILS at the time this procedure was designed) and the designer came up with this solution to get a LNAV/VNAV minima of 339' AGL and a LNAV minima of 703' AGL which were pretty good considering the terrain, obstacles and airspace restrictions (thanks Ebury) he had to deal with. He did a good job in the end.

If you have any other questions please ask.
User avatar
Iceberg
Too Tousand
Too Tousand
Posts: 2444
Joined: Mon Sep 05, 2011 1:09 pm
Closest Airfield: FAWB
Location: Pretoria
Has liked: 4 times
Been liked: 2 times

Re: FALA RNAV approach Rwy 07

Unread post by Iceberg » Thu Jan 17, 2019 12:06 pm

The latest Jepp plate differs slightly. It does not mention the 'VNAV only' at the SDF.
The 5630 is the altitude at 3.3nm to LA1MP on a 3% slope and is not a DA or MDA which depends on what capability and climb gradient you have. My 2c.
The sky is not the limit....
ZS-MDK
Karl Eschberger
User avatar
Induna
1k poster
1k poster
Posts: 1020
Joined: Tue Mar 20, 2012 10:01 am
Closest Airfield: FASD
Location: Port Owen - Western Cape
Has liked: 0
Been liked: 0

Re: FALA RNAV approach Rwy 07

Unread post by Induna » Thu Jan 17, 2019 12:41 pm

On LA1N1/2/3 it has a hard line below FL090, which means that you should not be lower than FL090 when arriving at any of these points. The hold at LA1N2 is between FL090 - 7700ft (and not below). As I understand the plate you cannot be below FL090 when arriving at any of these positions.

Correct?
Jacques van der Westhuizen
ZU-xxx | VANS RV-8 in the making...
ZS-WSW | Sonerai 2L
User avatar
Hop Harrigan
Frequent AvComer
Posts: 954
Joined: Tue Jun 01, 2010 7:55 pm
Has liked: 0
Been liked: 6 times

Re: FALA RNAV approach Rwy 07

Unread post by Hop Harrigan » Fri Jan 18, 2019 12:25 pm

tansg posted
No they aren't. The F090 is for the aircraft to fly the constant descent approach of 3degrees from beginning to end. Nothe the TAA for that sector is 8400' and that the levels in the hold are F090 - 7700' (hard minimum = not below 7700' indicated the line under the 7700').

Hi tansg,
But there is also a hard line under the ‘F090’ at LA1N2 so as Induna says, doesn’t that mean ‘not below this alt’? Note tha I was instructed to ARRIVE at LA1N1 at 8000’
Hop
There is no gravity...the Earth sucks
highline
Reaching altitude
Posts: 235
Joined: Fri Aug 26, 2005 8:16 am
Has liked: 0
Been liked: 0

Re: FALA RNAV approach Rwy 07

Unread post by highline » Fri Jan 18, 2019 2:03 pm

My take:-
Take a look at the Jepp JHB Radar Mins Chart 50 nm and you will see it is 8000 ft for that area (Lanseria +-25nm) hence radar allowing you down to that altitude so no ATC not busting their own Mins.
This CAA chart is very missleading as it suggests that if you at 7700ft at LA1T1 it will give you a continuous descent. This by my calculations is incorrect. The FAF is a must be altitude of 6700 ft. so 5.1 nm back to LA1T1 would put you at +-8400ft (TAA Alt) and +-10500ft at LA1N2 if you wanted to do a continuous 3 descend from LA1N2.
Nothing stops you from being higher at either as depicted on the chart to make this continuous 3dec descend.
Look a the Jeep chart for this and is much clearer.
high fly
User avatar
Hop Harrigan
Frequent AvComer
Posts: 954
Joined: Tue Jun 01, 2010 7:55 pm
Has liked: 0
Been liked: 6 times

Re: FALA RNAV approach Rwy 07

Unread post by Hop Harrigan » Sat Jan 19, 2019 8:30 am

Hi tansg,
Is Highline correct re the descent profile?
Hop
There is no gravity...the Earth sucks
User avatar
Iceberg
Too Tousand
Too Tousand
Posts: 2444
Joined: Mon Sep 05, 2011 1:09 pm
Closest Airfield: FAWB
Location: Pretoria
Has liked: 4 times
Been liked: 2 times

Re: FALA RNAV approach Rwy 07

Unread post by Iceberg » Sun Jan 20, 2019 12:12 pm

As Highline stated the Jepp version of the charts are clearer. The F090 values are not underlined. One should not read meaning into the underlining that is not there. Unless I am missing something?

My interpretation: use the F090 as the planned level of arriving at LAIN1/2/or 3.
Radar is required, so Radar could take you down to 8000ft if that fits in better with other traffic.
The sky is not the limit....
ZS-MDK
Karl Eschberger

Return to “Instrument Flying”