VORDME approach, NDB approach or ILS approach.

[744pilot 0]

If an airfield has an ILS then most pilots will use the ILS but when do they use the VORDME or if avail. the NDB approach instand of the ILS???THanks,

[Guest Tim__757]

R-Well, ATC will assign the type of approach to be used based on a number of different factors...First is weather such as winds, visibility, ceiling-the runway may have a CATIII ILS approach but if it has a 12G40Knt direct crosswind another runway with less capable approach would be used. You can also get assigned an ILS to one runway with a "circle to land" on another runway (Chicago MDW is a fun one for this).Then runway lengrth and condition of the runway enviromentThen any noise restrictions that might be in effect for a given hourRadio outages of land based navigation facilitiesTraffic consideration and airspace restrictionsLocal custom..at larger airports a ATC may elect to use a non-precision approach to a runway that is closer to the airline's gates to cut down taxi-timesAs always, the PIC may wave-off an approach assignment and request something different--this is easy to do at a less-busy field--but at ORD or LGA is rarely is done without good reason.Tim__757

[744pilot 0]

Yeh but sometimes I hear that they get a visual app because the WX ik good, but the pilot still flies the ILS.Thank for you reply,

[Guest tmetzinger]

>Yeh but sometimes I hear that they get a visual app because>the WX ik good, but the pilot still flies the ILS.>>Thank for you reply,A visual approach does not preclude a pilot from using the localizer and glideslope for guidance.A visual approach puts all the responsibility for finding the airport, avoiding other aircraft, and avoiding terrain on the pilot. There is also an expectation that the visual approach will be flown a bit tighter and faster than a precision or non-precision approach, so the crew is expected to get the aircraft on the ground and not dawdle around.Visual approaches are great tools for increasing traffic flow on good weather days at busy airports.As for the other approaches, they are often assigned based on the runway in use or desired by the crew, as well as the relative position of the aircraft to the airport.

[Guest Soulman]

You will find the majority of the time, when visual the pilots will fly a visual approach with the ILS as a back up.So say it's a nice day, with some cumulus at around 3000ft. The pilot will dial up the ILS, track it until visual, then revert to using the ILS as a backup. Have spoke to a Singapore 744 Captain who uses this method, only flying ILS approaches when the weather gets bad enough. Then there are the long-haul fellas who are required by company SOP's to perform an ILS after xx hours flying. Say after a 13hr stint Hong Kong - London perhaps?Have you seen the ATIS with such information:SYDNEY TERMINAL INFORMATION GOLF Approach: EXP ILS APCH THEN INDEPENDENT VISUAL APCH Runway: 34L AND R FOR ARRS AND DEPS Operational Info: PARALLEL RWY OPS IN PROG. INDEPENDENT DEPARTURES IN PROG. RWY 34L GP OUT OF SERVICE Wind: 340/15-20 As you can see, the pilots are required to perform an ILS approach, but once visual, they can perform a standard visual approach.Hope this helps.

[Guest Tim__757]

R-Yes, you are correct on the visual approach--but our RW operations manual has a little statement in there that says something like, "...if available, the PF will follow the projected glideslope on visual approaches." It is cheap insurance and easy to do.One thing to watch out for when flying a larger aircraft such as a 747 is the height at wich your main gear crosses the end of a runway on a standard approach.few feet off and you may stick your mains in something other than runway.Also the VASI lights will align the same as the ILS slope.Tim__757