timwintle1979 wrote:
Regarding using the GPS, I have tried this but 2 things confuse me about it, firstly what are all the different approaches ie NDB approach, VORDME approach, ILS approach etc and then their variations such as Bravo, Mike, Sierra etc etc.
Tim 🙂
The objective of the different approaches is to get you to decision height lined up on the runway at the same time as
1. keep you clear of high ground and obstructions
2. keep traffic separated
3. comply with noise/environment rules
.... all assuming that you cannot see a thing.
The approaches are chosen depending on a match between working airfield nav equipment and working aircraft nav equipment, combined with the direction of arrival.
At London Stansted there is a published approach to the airport from Barkway VOR It is the same pattern for all aircraft from Barkway to Stansted, but how do you approach Barkway? . The letters after the approach indicate different approaches to get to that initial point. I might use Barkway 1A if coming from Ireland (West) or Barkway 1B if coming from Europe (East). So the approach planning has to start a long way out.
If you arrive at the airport to discover there is no ILS then ATC is not going to be pleased with you, unles it has broken down in the last 5 minutes.
If the airfield has ILS Cat III, VOR and DME you cant fly that approach chart if you only have an NDB sensor working on the aircraft, because the approach requires you to make altitude or heading changes at particular distances, and if you don't know the distances you cant comply.
Airports will have many approach patterns defined because they have to cope with aircraft arriving from all different directions with all sorts of different equipment and the pilots choosing different approach strategies.
The charts will be designed so that pilots can be on any or all of the approach strategies and still achieve the 3 primary objectives.
Approach patterns will include a compulsory hold and descent at a waypoint to allow the pilot time to descend or a discretionary one when ATC call for it to get all the "ducks in a row" for landing.
At London Stansted in UK there is a compulsory hold if you are approaching from Ireland, for example at Barkway VOR. This is because aircraft have to stay high to keep clear of the approaches to London Luton, then they arrive at Barkway which is quite close to Stansted. ATC realise 747 pilots cant descend 8000' in 4 miles without having 400 screaming passengers rioting in the aisles, so the aircraft is sent out on a hold pattern to the north to give it time to make a comfortable descent to loop around and establish on the ILS.
Is it possible to land the 737 without ILS and without approach plate information? Yes, of course. You have the GPS. It contains a surprising number of approach patterns for a surprising number of airports. Many are unrecognisable as official ones, but I havent found one that flies me into a mountain yet.
You are procedurally not allowed to use the GPS to fly approaches because it is not approved for height and the GPS doesnt give you height info, but the GPS will give you approach pattern info. If you select the destination airport and then click PROC on the GPS you will get a selection you have clearly spotted before. The approaches with NDB or VOR will give you the pattern. Select one of those and load them. Look at the GPS readout and you will see the key waypoints to follow ( remeber they are shown bottom up, earliest to latest) Read off the navaids and the heading to fly to/from any of them. Get the frequencies for the navaids - the FS9 MAP function can help. (when learning, judicious use of the pause key can help here)
By tuning in the correct track on the OBS bearing and the correct frequency on the NAV1( select NAV and use the COURSE setting - not HDG and HDG setting on the AP), you can follow the indications on the VOR instrument to keep to the pattern and make the turns at the correct time. The autopilot will follow the tracks and backcourses you put into the OBS bearings. How to fly a VOR approach is beyond the scope of a forum chat response, but once the autopilot has lined you up on the runway, you are on your own regarding descent angle, speed, and staying on line.
VORs give you track info to the VOR, not the runway, and if you track religiously to the VOR course all the way down you will find yourself landing on a small red shed near the airport, not on the runway. The GPS pattern, as opposed to a chart, doesnt show decision heights, so if you are descending in low vis on a VOR I would like be able to see the runway from at least 2 miles and 1000 feet up so I can make last minute adjustments.
Give yourself time, so get the speed right down early, flaps and gear out and approach carefully and slowly. ATC (on IVAO - not real) has often asked me to slow down, but never to speed up. You can tell them to get lost anyway - you are in control. 😂
Hope this helps.