Direct to on RNAV procedure

[Andrew_Flora]

Direct-to question:

How should I flown a waypoint, marked as FLY-OVER on RNAV procedure (STAR) if ATC cleared me to fly to THE point by DIRECT-TO method?
Actually, it has been flown as fly-over.

How do it the modern FMS?

Thank you.

[easyme]

depends on the aircraft you fly;

I believe on the Airbus you are able to select 'fly-over' but this is not possible on the Boeing 737. Our procedures call for us to use HDG SEL to ensure flying over waypoint before intercepting LNAV track back using LNAV.

[B-HKD]

Correct me if im wrong, but shouldnt the fly-over waypoints (RNAV) be hardcoded into the FMC with the SID/STARS? (As long as the AIRAC is current)

[easyme]

They are hardcoded in the FMC but if you go Direct-to to a waypoint it automatically changes it to a fly-by point. (at least on the B737NG I fly)

[Andrew_Flora]

So, would it correct to fly FLY-OVER-waypoint as FLY-BY if I have clearance to Direct-to?

May be, in some cases, it need to be flown as fly-over anyway?

[PappyJ]

I'm a little confused about your question. However, i'll take a stab at what I surmise it to be.

You're cleared direct to XYZ. You chose DIR and the aircraft points itself in that direction. As you get closer, your aircraft begins to turn without actually flying over XYZ. Is this what you're talking about?

If so - and it's an Airbus - its due to the load factor (Rate) during the turn (Normal Law limits) from track to track.

If overflying XYZ is necessary, select the Over-Fly key. It will then over-fly XYZ, then it will perform a return to track manoeuvre after passing XYZ.

[Rosberg]

Flying on 737NG this trick can be used to ensure a waypoint is flown over instead of by.
Create a second waypoint a short distance (0.1 miles) along the track you intend to fly right next to the point you want to fly over. That way the turn will not be started until the first fly over waypoint has been passed.

[easyme]

A good trick but I believe when you are flying a PRNAV procedure you are not allowed to create waypoints - you must use existing ones.

I stand to be corrected on this one of course!

B-HKD; you are correct in saying that fly-over points are hard coded in the FMC. What I am trying to say is that on the 73 they will change from a fly-over point to a fly-by point when you are using the direct-to function. On a PRNAV departure you are still obliged to fly-over and that is why HDG SEL is used.

[Andrew_Flora]

Yes, sure, in accordance with TGL-10, when you're flying PRNAV procedure you are not allowed to modify or insert waypoints. That's true. That's why, I think, when I choose DIR function, my FMC (neither Collins nor Honeywell) actually flew over the waypoint, hardcoded as 'Fly-over'. It's flying only as hardcoded, without modifying 'fly-over' to 'fly-by' in DIR mode.
In my case, it was unexpected for me and ATC, because after DIR my plane overflew the waypoint and thereby overshoot the track.

[Pontius's Copilot]

Next time it happens, tell ATC it's coded as a FLY-OVER and ask if they expect you to do that.

[DJ77]

If ATC clears you "direct to XYZ" in a PRNAV SID or STAR, you are no longer following an RNAV procedure. Hence if ATC still requires you to overfly XYZ, he should mention it.

[LLLK]

I tend to agree with Pontius's Copilot. The waypoint is fly-over to meet some procedure design requirement (route spacing, noise routing, obstacle clearance etc) and it may not be appropriate to fly-over it if you are approaching from a different direction, as in a DCT. ATC should know that the waypoint is fly-over (there shouldn't be many in P-RNAV procedures) and why it is fly-over. They should also not be surprised if some aircraft fly-over and others fly-by - there is nothing in TGL 10 or any of the RNAV specs about how to treat this so inevitably different avionics do it differently. TGL 10 does say that the crew cannot alter the procedure (no manually entered waypoints) Best idea? ATC should not give DCTs to fly-over waypoints and procedure designers should minimise their use.

[aterpster]

You guys give ATC a lot more credit for understanding procedural nuances than I do.