View Full Version : Approaches
TurboTomato
2nd Feb 2012, 09:08
Question for the pilots - reading the thread about the 777 off the runway at Munich, it's got me curious.
Maybe this is too much of a 'general' question as it is weather dependant, but what type of approach is considered routine? By that I mean do you almost always do ILS approaches with the occasional visual and autoland? And during ILS approaches, do you mainly hand-fly the aircraft following the ILS bugs or do you use some kind of approach hold?
I'm not an airline pilot but I'm pretty sure every so many approaches has to be hand flown. From a private pilot point of view it's always better (IMO) to go for a precision approach which is either ILS or PAR rather than non precision such as NDB/DME or SRA. The minima are lower for precision approaches so you have more chance of spotting the runway if it's really claggy, plus they're easier to fly than NDB approaches. The vast majority of GA a/c don't have autopilots, (I'm talking about your single engine spamcan type here, not multi engined zillion quid stuff) so it's hand flying all the time.
Bear in mind of course that the only approach some airfields have is NDB.
Edit: Sorry missed part of your question. There are several varieties of ILS coupled autopilots around. Some are certified to take you down to minima (usually 200 ft on QFE) and then you have to initiate a go round if the runway is still not in view; then there are the all singing and dancing ones that most of your 'proper' airliners have which will land you on the runway, keep you straight and apply the brakes for you while you chat up the stewardess with the lovely erm, eyes.
You can tell if an airliner has made an autoland because they are usually the smooth landings...:)
If you're really interested then you will find out all you need to know in here http://www.amazon.co.uk/Radio-Navigation-Instrument-Flying-Pilots/dp/1843360691/ref=sr_1_4?ie=UTF8&qid=1328204105&sr=8-4. Bear in mind it's not a lightweight read....
Flying 737s across europe and northern africa in 99% of all approaches we fly an ILS. We do not care if we have to fly an NDB or RNAV approach, there are different limitations, but the indication and operation is exactly the same as on an ILS, so the difference is minor. At the moment we sometimes are limited using those as the lower BARO VNAV minima (lower than the usual non precision) can in many cases only used down to a surface temperature of -15°C.
Anyway, an ILS is usually flown either completely or partially in manual flight, however many pilots elect to use the flight director for it. So called "raw data" approaches are still flown, but not as often as flight director approaches. Autolands are quite rare, mainly during fall and spring, sometimes winter as well when fog is encountered more often. We can, unlike other companies, do an autoland even though low visibility procedures are not in force, but that is extremely rare. Autolands, especially in non-LVP environments, are more intense than normal landings, one needs to be very focused and constantly check the whole aircraft system for any developing faults or problems to take over in flash.
Most of us simply love flying a visual approach, not only that one can save considerable time and fuel, its just plain fun. However over here in germany pretty much every airport with some commercial traffic does not allow visual approaches anymore, mainly because of noise restrictions. Therefore visual approaches are somewhat rare for us.
From a Long Haul POV you'll be lucky to fly more than 2-3 approaches a month so most pilots I know of hand fly if circumstances (e.g weather/ familiarity with airport/ATC/fatigue) permit. Most use the Flight Director, though if it's a good day at home base (known environment, benign ATC) we'll consider Flight Director off. As far as the landing itself is concerned I reckon I only autoland a couple of times a year on the aircraft, if that - many runways/airports don't have the equipment to allow it, even if they do if the weather is good it may not be a good idea because the "protections" may not be in force ;) , and in any event why give the landing "away" to the autopilot when you don't have to????
Finally as Denti rightly said most major international airports don't allow genuine self positioning for a visual approaches any more, so 99% of the time you'll be radar positioned for an ILS - whether you're able to turn that into a straight in visual obviously depends on the situation on the day.
We do not care if we have to fly an NDB or RNAV approach, there are different limitations, but the indication and operation is exactly the same as on an ILS,Interesting, I don't know a lot about airline instrumentation but how do you get elevation info from an NDB approach? I have to fly them using the ADF and set rate of descent as per the plate.
I was under the impression that precision approaches were precision because you got both elevation and azimuth info whereas with non precision you only got azimuth. Be gentle, I'm not a pro, just a weekender with an IMCR.
Many FMCs have have stored non-precision approaches in three dimensions - crossing heights at the FAF and Missed approach point and a nominal glideslope.
If you fly such an approach on some aircraft then dependant on your displays you may get left/right and up/down indications on your PFD and ND very similar to that which you get on an ILS. In reality you're flying an RNAV approach overlying a radio aids procedure (and most operators demand the radio aid is montored).
Ah, got it thanks. You guys have it easy really don't you! When I was doing my rating I was doing a hold in a particularly bad crosswind and turbulence, feet and hands going like a steam engine and I asked my instructor who flies 747's for a day job how they manage it. 'I press a button' was his reply....
Sshh, don't give all our secrets away:ok:
Happy Landings....
Yup, i guess we all had to do the very basic stuff in flight school (well, before they bought those all glass cockpit planes, G1000 is a curse for initial IFR in my opinion). Stepping into a jet thereafter made many basic IFR thing a lot easier, like holds, non precision approaches and so on. Even something simple as the track line which provides always a no-wind situation is a huge help. But FMC procedures and newfangled options like IAN help a lot.
However, there is always the operational side of commercial flying and that can take up the main part of our concerns and time by now. The focus shifts quite a bit. IFR flying is taken as granted (but should be trained as much as possible) while other decisions take up more and more of our time.
In reality you're flying an RNAV approach overlying a radio aids procedure (and most operators demand the radio aid is montored).
True, it is in reality an RNAV procedure. However we do not have to monitor the nav aid anymore, although it is considered good airmanship and recommended to do so, just not required anymore.