Controller-Pilot Q on FMS/FMC's

Vector4Food

This job would be easier without all the airplanes
Just a short question on on-board flight computers.

If you put in a direct waypoint on your route( A-B-C now A-C), or input a route into the system but do not execute it, can you see the new estimated arrival time? If you do see that time, does the computer factor only the current winds aloft, or does it get information also from forecasted winds?

I know different types use pretty different FMS' but perhaps some people could elaborate?

Thanks
 

Baronman

Well-Known Member
I'm only speaking for the ERJ with the Honeywell FMS.

Nope, prior to activating a "direct to" it doesn't estimate new arrival times. We initialize wind data and temperature data on the ground which will start the FMS off with some info as the flight begins. As the flight progresses it uses current wind data/fuel use etc to predict an arrival time. Basically it uses the initialized data to start and then "learns" the new winds and "forgets" what we initialized.

The only estimations the FMS will do is based on changing winds and altitudes. For instance and time we consider cruising at a different altitude and or know the winds at a different altitude, we have a "What-If" page. We input the new data (wind/cuise alt/temp) and the FMS will provide a new ETA and Fuel at arrival. Following that there is an option to activate.

I guess our system isn't as advanced as Boeing/Airbus equipment. They're also flying significantly longer legs where the info would be of greater importance.
 

Vector4Food

This job would be easier without all the airplanes
I'm only speaking for the ERJ with the Honeywell FMS.

Nope, prior to activating a "direct to" it doesn't estimate new arrival times. We initialize wind data and temperature data on the ground which will start the FMS off with some info as the flight begins. As the flight progresses it uses current wind data/fuel use etc to predict an arrival time. Basically it uses the initialized data to start and then "learns" the new winds and "forgets" what we initialized.

The only estimations the FMS will do is based on changing winds and altitudes. For instance and time we consider cruising at a different altitude and or know the winds at a different altitude, we have a "What-If" page. We input the new data (wind/cuise alt/temp) and the FMS will provide a new ETA and Fuel at arrival. Following that there is an option to activate.

I guess our system isn't as advanced as Boeing/Airbus equipment. They're also flying significantly longer legs where the info would be of greater importance.
Thanks for the reply Baronman,

Reason I ask, the airlines have stressed the fact that the routes given to their crews are the most economical for their flight, even though the route may be 100-200NM longer in some cases... however a lot of the time these airlines base this on their own weather forecasting, which isn't always correct.

Anyway thanks for the reply again.
 

Chief Captain

Well-Known Member
In some parts of the world, airlines may file slightly longer routes to avoid navidation charges imposed by FIRs along the way.
 

tykrtr

Well-Known Member
Here's another question for you RJ (CRJ or ERJ) FMS people: To proceed direct to an outer marker, will you have the ILS loaded even if the weather is clear (and therefore is it a matter of pressing just a couple buttons), or do you have to enter the whole identifier?
 

cime_sp

Well-Known Member
Here's another question for you RJ (CRJ or ERJ) FMS people: To proceed direct to an outer marker, will you have the ILS loaded even if the weather is clear (and therefore is it a matter of pressing just a couple buttons), or do you have to enter the whole identifier?
Well, that's a different thing altogether. In the CRJ the ILS is almost always loaded into the box if there is one.....even for a visual approach. But by the point where we are being vectored for the approach we have switched to "green needles" which means using the ILS NAV receiver as the active navigation source although we are waiting for the Localizer to center. It is kind of a pain if the controller then gives you direct to the outer marker. There are a couple of ways we can do this....

1. Change your navigation made back to RNAV "white needles" and go directo the the LOM. Most of the time this is not done since you will only have switch it back in a second or two.....and it removes the ILS localizer from view

2. If the Outer marker still works....in many places it doesn't, we'll pull up the NDB RMI needle. This is usually not done though because it clutters up your CDI, and is remarkably inaccurate.

3. Stay in "green needles" with the ILS Localizer pulled up. Have the PNF enter direct to the OM in the FMS and navigate with heading mode using the FMS RMI needle. Usually not done because it requires a lot of typing and needle switching etc...

3. Continue operating in "heading mode" and eyeball the heading needed to go direct to the OM via the MFD. This is what is done probably 80%-90% of the time when given this clearance a few miles from the OM. If given direct to the OM from 20-30 miles away that's a different story though. You will be within probably a few degrees of the required heading and involves the least amount of error-causing last minute frequency changes, needle changes, nav mode changes, etc.... It also allows you to spend more time outside the cockpit flying the airplane visually instead of having to come back inside and change navigation modes, verify FMS inputs by the PNF, etc.

Just my opinion here but the easiest/safest thing from a pilot standpoint would a cleareance something like this....

"fly heading 235 to intercept final at the outer marker cleared for the visual approach runway XXX" This puts me right where you want me over the OM and in no way makes me want to/have to change any of the set-up already done in the cockpit. Also it tells me exactly what you want me to do.
 

tykrtr

Well-Known Member
Thanks for the response. We have several controllers, including me, who tell pilots (30-40 miles out) to go direct to an outer marker, and I didn't know if it was actually easier or something someone made up. I have flown with an old GPS and it is a pain in the ass, so I have tried to tell everyone not to do that unless the airplane has some sort of FMS that would make it easier. Of course, if you're within 20 miles, I tell them to pick a heading cuz its easier to move the heading bug.

Thanks again.
 

cime_sp

Well-Known Member
Thanks for the response. We have several controllers, including me, who tell pilots (30-40 miles out) to go direct to an outer marker, and I didn't know if it was actually easier or something someone made up. I have flown with an old GPS and it is a pain in the ass, so I have tried to tell everyone not to do that unless the airplane has some sort of FMS that would make it easier. Of course, if you're within 20 miles, I tell them to pick a heading cuz its easier to move the heading bug.

Thanks again.

30-40 miles out is no problem. We'll just use the FMS for that one.
 

Juliet Lima

New Member
"fly heading 235 to intercept final at the outer marker cleared for the visual approach runway XXX"
why the F are u being vectored to the outer marker AND cleared for a visual approach?? does this make any freakin sense to u?? it makes none to me.

u freakin pilots...want ur cake and eat it too. :banghead:
 

dc3flyer

Well-Known Member
Just a short question on on-board flight computers.

If you put in a direct waypoint on your route( A-B-C now A-C), or input a route into the system but do not execute it, can you see the new estimated arrival time? If you do see that time, does the computer factor only the current winds aloft, or does it get information also from forecasted winds?

I know different types use pretty different FMS' but perhaps some people could elaborate?

Thanks
I am not an airline guy, but for another answer....

We don't input any weather information into the FMS. Once we start moving it calculates our groundspeed and current winds and all info we get from the FMS (including arrival time) is based on those winds and that groundspeed.

Here's another question for you RJ (CRJ or ERJ) FMS people: To proceed direct to an outer marker, will you have the ILS loaded even if the weather is clear (and therefore is it a matter of pressing just a couple buttons), or do you have to enter the whole identifier?
Again, not an RJ driver but.... We do not typically have the approach loaded in VFR conditions (unless it is somewhere we KNOW we will be given the approach anyway, such as Teterboro) so if you were to clear us to the outer marker, we would have to look it up on the approach plate and then type in the identifier on the FMS, or we could just load the approach.
 

cime_sp

Well-Known Member
why the F are u being vectored to the outer marker AND cleared for a visual approach?? does this make any freakin sense to u?? it makes none to me.

u freakin pilots...want ur cake and eat it too. :banghead:

It actualy happens quite a bit and we don't ask for it. It's mostly for the benefit of the controller. Them having us intercept final at a certain point in order to give them the spacing they need from the traffic in front. Also, as another poster stated....at night at busy airports it is not uncommon to have the field in sight but not the traffic to follow.

A clearance such as "intercept final at the OM, cleared for the visual" or "turn 320 to intercept 5-mile final" are fairly common clearances at some fields. Or you can be 20-30 miles away and be given direct to the OM and told to report the filed in sight. Once you do you get cleared for the visual.....either way the techniques I described earlier work for all of them.
 
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