enrico10999

What approaches do you use: ILS / LOC/DME / RNAV

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Hi everybody

I use the PMDG 737 NG in P3DV4 and trying to get the procedures as realistic as possible.

Here is my questions: 

"What approach procedure (ILS/LOC/RNAV) does the crew use and who decide it?"

"How long is the pilot flying the respective approach by autopilot, from what point does he have to turn of the AP and have to fly by hand?

Sorry if my english is not so good, I am originally from Germany :-)

Here my "dangerous half-knowledge":

- ILS - The plane captures after the satellite-based waypoints of the STAR  the two "guiding beams° of the runway for lateral and vertical guidance and could perform theoretically an automatic landing.

What is to do: 

- program the STAR and ILS Approach in the FMC, select a Flap/Speed (40/145) setting at the REF Page

- get a "logical" flight path in the FMC, reduce the programed speed at the FAF (Final Approach Fix) to Flap 15 Speed (VREF +15) where the ILS will be captured

- turn in the ILS Frequencies at NAV 1 and 2 

- turn in the ILS Course at both Course knobs 

- shortly before capturing the Glideslope, push LOC and than APP

- Airplane will hopefully descend to the runway along the ILS glide path.

- deactivate the Autopilot at 2000 ft (???) above ground and landing by hand or do an Autoland 

 

- NDB approach - a non-precision approach where an omnidirectional beacon is displayed on the  
  ADF display, often in conjunction with DME, which indicates the distance to the Runway 

- VOR/DME - a non-precision approach where the directional beacon VOR provides lateral guidance, 
  but does not provide any information about the glide path. DME (Distance Measuring Equipment) 
  indicates the distance to the Runway 

- LOC/DME - the localiser provides lateral orientation, but no glideslope for vertical guidance, 
  the DME shows the distance to the runway and corresponding charts with distance / altitude help the pilot
 to get the vertical alignment of the approach.

What is to do:

- program the LOC Approach in the FMC 

- tune in the LOC Frequency at NAV 1 and 2

- tune in the RWY Course at the Course Knobs

- before the FAF reduce the ALT to the Minima

- before the FAF push the LOC Button 

- hopefully the Airplane will descend to the RWY 

- switch of the AP before Minima or at 2000 ft (???)  and fly by hand

- RNAV - Satellite-supported area navigation with freely selectable waypoints.
  RNP makes a statement about the accuracy of navigation performance.
  0.3 stands for maximum deviation of 0.3 NM, 
  The waypoints lead at the approach to the minima where the pilot has to see the runway und fly the last part by hand

What is to do:

- program the RNAV Approach in the FMC 

- reduce the ALT before the FAF to the Minima to allow the Airplane to descend 

- Fly the Descend with AP and LNAV/VNAV active

- before the Minima turn of the AP and fly by hand

 

It would be nice if you could add some information or correct me where I am wrong!

Thanks !

Erik

 

 

 

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In my world (not B737) the aircraft was set up for RNAV to the LOC for ILS.  At five miles it was gear, flaps, slats and brakes.  At one thousand agl the aircraft had to be stabilized with either all auto or all manual.    

Grace and Peace, 

 

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Posted (edited)
39 minutes ago, enrico10999 said:

Hi everybody

I use the PMDG 737 NG in P3DV4 and trying to get the procedures as realistic as possible.

Here is my questions: 

"What approach procedure (ILS/LOC/RNAV) does the crew use and who decide it?"

- If the aircraft/pilots capability can do all of them, we will use the best one of all if available.

"How long is the pilot flying the respective approach by autopilot, from what point does he have to turn of the AP and have to fly by hand?

-Besides autoland which keep AP until vacating the runway, turning the AP off depends on company policy and/or pilot favor.

Sorry if my english is not so good, I am originally from Germany 🙂

Here my "dangerous half-knowledge":

- ILS - The plane captures after the satellite-based waypoints of the STAR  the two "guiding beams° of the runway for lateral and vertical guidance and could perform theoretically an automatic landing.

What is to do: 

- program the STAR and ILS Approach in the FMC, select a Flap/Speed (40/145) setting at the REF Page

- get a "logical" flight path in the FMC, reduce the programed speed at the FAF (Final Approach Fix) to Flap 15 Speed (VREF +15) where the ILS will be captured

- turn in the ILS Frequencies at NAV 1 and 2 

- turn in the ILS Course at both Course knobs 

- shortly before capturing the Glideslope, push LOC and than APP

- Airplane will hopefully descend to the runway along the ILS glide path.

- deactivate the Autopilot at 2000 ft (???) above ground and landing by hand or do an Autoland 

-When you are clear for the approach, you can  arm APP and still following the STAR until the aircraft capture LOC and then GS. Some wait until aircraft is within 90* of final approach course to arm, some just arm it whenever they are clear for the approach. 
-IF in the 737 you need to arm LOC before APP then you should do it early since the principle is to capture LOC before GS (but my best guess is you can arm APP and it will arm both LOC and GS)

-After capture the GS set the go around altitude for miss approach procedure

- NDB approach - a non-precision approach where an omnidirectional beacon is displayed on the  
  ADF display, often in conjunction with DME, which indicates the distance to the Runway 

- VOR/DME - a non-precision approach where the directional beacon VOR provides lateral guidance, 
  but does not provide any information about the glide path. DME (Distance Measuring Equipment) 
  indicates the distance to the Runway 

- LOC/DME - the localiser provides lateral orientation, but no glideslope for vertical guidance, 
  the DME shows the distance to the runway and corresponding charts with distance / altitude help the pilot
 to get the vertical alignment of the approach.

What is to do:

- program the LOC Approach in the FMC 

- tune in the LOC Frequency at NAV 1 and 2

- tune in the RWY Course at the Course Knobs

- before the FAF reduce the ALT to the Minima

- before the FAF push the LOC Button 

- hopefully the Airplane will descend to the RWY 

- switch of the AP before Minima or at 2000 ft (???)  and fly by hand

The final approach course of the non-precision approaches often differ from the runway course so if you shoot the approach you will use the final approach course until you have the runway inside, turn off the AP and set runway course.

-After passing the FAF you will set the GA altitude.

- RNAV - Satellite-supported area navigation with freely selectable waypoints.
  RNP makes a statement about the accuracy of navigation performance.
  0.3 stands for maximum deviation of 0.3 NM, 
  The waypoints lead at the approach to the minima where the pilot has to see the runway und fly the last part by hand

What is to do:

- program the RNAV Approach in the FMC 

- reduce the ALT before the FAF to the Minima to allow the Airplane to descend 

- Fly the Descend with AP and LNAV/VNAV active

- before the Minima turn of the AP and fly by hand

It would be nice if you could add some information or correct me where I am wrong!

Thanks !

Erik

 

 

 

Hi,

I'm not type rated in the 737 but in the A320/321 so hopefully some of my info will help you. I haven't flown the 737 (in simulator) for a very long time so I might be wrong here and there.

Cheers.

Edited by Hoang

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Airliners typically fly ILS approaches, GA aircraft will often fly RNAV (GPS) approaches.  ILS approaches are mainly installed at major airports, RNAV approaches are available for many smaller airports..

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Pilots can put a request in for a certain type of approach but it is normally ATC who dictates the type of approach in use.

VOR & NDB approaches now tend to be flown in a very similar way to RNAV approaches using LNAV & VNAV rather than HDG & V/S like in the past. The raw data from the beacon is still required to be displayed and is the overriding criteria.

RNAVs are useful for times when an ILS is out of service or for flying a visual segment under guidance. 

It’s type specific but some aircraft will require the use of an autopilot to fly an RNAV due to the resolution of the flight directors being limiting in manual flight.

In addition, again type specific. You maybe unable to utilise the full RNAV minima. For example the B747-400 cannot fly legally below 360ft AGL unless on a coupled (ILS) approach, so 360ft becomes your absolute minimum. Of course in reality the aircraft could go much lower however it was only originally certified to this height during flight testing. Boeing deemed it uneconomical to recertify the aircraft given its now limited lifespan remaining.

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2 hours ago, enrico10999 said:

"What approach procedure (ILS/LOC/RNAV) does the crew use and who decide it?"

The most accurate one available. Most accurate is the ILS which is always the one picked when it's available. Even on a visual you typically tune in the ILS to have full guidance. The order is ILS - RNAV - LOC/DME - VOR/DME - NDB - visual.

2 hours ago, enrico10999 said:

"How long is the pilot flying the respective approach by autopilot, from what point does he have to turn of the AP and have to fly by hand?

Mostly company SOP. Like Wilhelm said, most will decide whether full auto or full manual by 1000 ft where the aircraft has to be stable for landing. Other than that, pilots will usually keep the AP on until the runway is in sight, then disconnect and fly manually. Keep it on in low visibility as it's best to let the AP fly and have both pilots monitor the instruments. Some carriers also have policies that require the use of AT until shortly before the threshold, even when the AP is off.

2 hours ago, enrico10999 said:

- ILS - The plane captures after the satellite-based waypoints of the STAR  the two "guiding beams° of the runway for lateral and vertical guidance and could perform theoretically an automatic landing.

What is to do:

If you set both NAV radios to the ILS frequency and engage both APs on final the airplane will do an autoland.

A STAR isn't requirement for an ILS, there are airports (mostly smaller ones) that don't even have STARS and you'll be vectored towards the IAF or FAF and establish on the ILS.

In the 737, the typical landing flap is 30 degrees. This again depends on company SOP too. Flap 40 is usually only used when you have a short runway and need a lower approach speed to reduce landing distance. As Flap 40 produces more induced drag it will require higher thrust to maintain the speed and thus burn more fuel which your typical company will frown upon. Also, stay away from Flap 40 in gusty and/or crosswind conditions as it will only exacerbate the gust/crosswind effects. Since you add a wind correction additive to your target speed in windy weather you will also be closer to flap limit speed because Flap 40 leaves less margin to the flap limit speed than 30. At Flap 30 you will also have more control when flying manually, at 40 it's kind of sluggish.

This will vary again from company to company, but I make sure to be configured and stable for landing before the FAF (gear down, landing flap, target speed, descent rate not more than 1000 ft and crossing the FAF at the published altitude, no full white or full red PAPIs on the entire final approach).

Arm LOC before GS. I usually arm them one by one as soon as localizer/glideslope are alive, not before they are. If both are alive you can go for it and arm APP which will arm both LOC and GS. There is an option in the NGX FMC where you can select if GS capture before LOC capture will be denied which is the most common config.

If you do it right, the airplane will definitely follow the ILS to the runway, no need to just hope 🙂

3 hours ago, enrico10999 said:

- RNAV - Satellite-supported area navigation with freely selectable waypoints.
  RNP makes a statement about the accuracy of navigation performance.
  0.3 stands for maximum deviation of 0.3 NM, 
  The waypoints lead at the approach to the minima where the pilot has to see the runway und fly the last part by hand

What is to do:

Not sure what you mean by 'freely selectable'. On an RNAV, nothing is freely selectable, always do what the published approach chart says.

Altitude on the MCP will typically be set to the next waypoint's published altitude on the RNAV approach to make sure not to bust any of those restrictions. Coming closer to the FAF with the altitude being set to the FAF altitude, set the altitude to the next hundred feet above minimums. As you cross the FAF and descend to minimums, set the go around altitude next. The FMC will be in approach logic by now so it won't interrupt the descend if you set a higher altitude. After crossing minimums, fly visually and recycle the flight directors to obtain guidance for a potential go around. The pilot monitoring should have the VSD displayed on his ND while the pilot flying will have progress page 4 opened on his FMC to monitor lateral and vertical performance.

You can fly an RNAV approach in LNAV/VNAV or LNAV only. RNAV, as opposed to an ILS, uses the barometric altimeter. With extreme temperatures your altimeter becomes inaccurate and won't show your actual altitude. This is dangerous when flying the RNAV in LNAV/VNAV in these conditions since VNAV relies on your altimeter and you will cross the waypoints at wrong altitudes. In this case, LNAV/VNAV is not applicable and you will fly the RNAV in LNAV only down to the LNAV MDA which is higher than LNAV/VNAV minimums. You can find the temperature limits for LNAV/VNAV on the RNAV approach plate (for RNAV GPS approaches, not RNAV RNP). RNAV RNP approaches will not be applicable at all when the temperature exceeds the limits. However, altimeter inaccuracies due to temperature are not simulated in the sim.

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Superb reply Niklas,👍 that I too have gleaned a great deal from.

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6 hours ago, enrico10999 said:

"What approach procedure (ILS/LOC/RNAV) does the crew use and who decide it?"

As others have said above: in the airline world, usually the operator will have guidance along the lines of "use the best approach available", which in general terms is going to mean:

  • ILS
  • RNAV
  • VOR
  • NDB
  • Circling/Visual

...in pretty much that order of preference. As others have mentioned, ATC and local procedures generally determine which approaches are in use at a particular airport at any given time (for instance, at Nice the offset VOR/RNAV approaches are used most of the time even though there is an ILS available because of noise concerns (the VOR/RNAV approaches are offset and keep the aircraft over the sea whereas the ILS would involve a longer straight-in final approach over populated areas). As such in that particular case the ILS would only be used if the weather conditons precluded the use of the other approaches). The crew can always request a different approach from that offered but one would need to bear in mind that doing so may incur delays if you have then be fitted in around other traffic.

6 hours ago, enrico10999 said:

"How long is the pilot flying the respective approach by autopilot, from what point does he have to turn of the AP and have to fly by hand?

There's no black and white answer here as it will depend upon airline-specific procedures and type-specific limitations as well as conditions on the day.

As Jon alludes, most types will have limitations published in the FCOM establishing minimum heights for autopilot engagement. For the A320, for instance, this is 160ft aal on a Category I ILS approach, or the Minimum Descent Height for a non-precision approach (i.e. everything else) (and, indeed, on the 320 the autopilot will automatically disconnect at the MDA on these types of approaches). So those are the absolute minimums (and will be different for different types as Jon notes). Obviously for an autoland (i.e. a Category II/III ILS) the autopilot is permitted to remain engaged throughout the touchdown and rollout -- this would normally only be done when the weather warrants it, however.

Beyond the absolute minimum heights above; well, it depends a lot. For instance, at one particular airline where monitored approaches are the norm, the second pilot would customarily fly the approach through the autopilot (but not always - it could equally be hand-flown from a long way out dependent on the situation and workload) until 1000R or visual (if later) at which point the landing pilot will take over and at some point before the minimum disconnect heights mentioned above ('some point' being heavily dependent on the individual themselves, the conditions on the day and so on), disconnect the autopilot and land manually.

For other airlines where the same pilot handles the whole sector, they might leave the autopilot in down to minimums or they might take it out at top of descent and hand-fly it all the way down, or something in between -- all dependent upon airline policy and above all the conditions at the time.

6 hours ago, enrico10999 said:

the ADF display, often in conjunction with DME, which indicates the distance to the Runway 

 

6 hours ago, enrico10999 said:

DME (Distance Measuring Equipment) indicates the distance to the Runway 

 

6 hours ago, enrico10999 said:

the DME shows the distance to the runway

Be very careful about this -- the DME readout shows you the distance to the DME station, which may or may not be situated at the runway threshold. Indeed, in the vast majority of cases outside of an ILS/DME approach, the DME will NOT be situated near the runway and may very well not even be situated on the airport itself. It is, therefore, very important that you study the chart closely (well before you actually start the approach -- this should all be briefed comfortably before top of descent - by the time you actually start flying an instrument approach you should be a world expert on the procedure!) to ensure you know where the DME is referenced from, what DME readings you expect to see and what heights you should be at, at various points along the approach as otherwise you may find yourself somewhere you don't want to be!

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24 minutes ago, skelsey said:

Be very careful about this -- the DME readout shows you the distance to the DME station, which may or may not be situated at the runway threshold. Indeed, in the vast majority of cases outside of and ILS/DME approach, the DME will NOT be situated near the runway and may very well not even be situated on the airport itself. It is, therefore, very important that you study the chart closely (well before you actually start the approach -- this should all be briefed comfortably before top of descent - by the time you actually start flying an instrument approach you should be a world expert on the procedure!) to ensure you know where the DME is referenced from, what DME readings you expect to see and what heights you should be at, at various points along the approach as otherwise you may find yourself somewhere you don't want to be!

Again, superb elucidation by you,Simon. Should go a long way to help the OP👍

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Hi,

Thank you very much for your answers and explanations!
With your help I have better understood the differences of the individual approach procedures! 

Yesterday I was in a 737 full flight simulator here in Berlin and we flew the LOC/DME RWY 26 in LOWI, with a circling to RWY 8. That was pretty exciting, after we captured the LOC, we switched off the autopilot at DME 16 and I flew down to the valley per hand. A challenge was the final 180° turn, because the steering horn behaves differently than my Hotas joystick at home and I got over the 30° bank angel and sank quite a bit, but we didn't crash and still reached runway 8...

Greetings Erik

 

 

 

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Brilliant, well done Erik, sounds like you had a fun day.

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