RTE 2
 

Hello,

747 armchair pilot but 300 hour realworld pilot would like to know genuine, real life reasons for using RTE 2 in the FMC.

I understand its for investigation of other routes, alternate airfield approaches or similar things, but is it used and if so, how and why might you use this?

I understand the FMC otherwise in good detail so feel free to use real terminology. I just fail to see at the moment why you would need it for back-up when you could otherwise update your active route to your second route, no? Or, I can't imagine why the route would change so drastically, so quickly, that you would need a second route option available.

Is this inputed at the gate like the normal FMC or is it optional en-route? I also read a RTE 2 should be left in the FMC at shut-down? Lots of confusing 'armchair pilots' spouting out info so I'd like it from the horses mouth if possible.

Thanks kindly for coming down to my level for a few minutes!

:O

I'm new on the 744 myself so I am still learning all the functions and quirks.

I have seen Captains copy the original route to RTE2 in case the first one gets FUBAR'd. I have seen some Captains put a special ENG out departure procedure in RTE2 if one might apply. That's all I have seen so far in the "real world".

I'm not familiar with the FMS of the Boeing series but think to grasp that this is just the secondary flight plan well known in the rest of aviation.

There are very good reasons to have a secondary flight plan and it is common practise and standard operating procedure to use it for example but not limited to:

- approach: arrival and runway not yet known, so you program the two most likely ones
- take off: One engine out as mentioned
- enroute: alternates, ETP (equitime points), especially for Etops flights: You always program what you would do this very moment if you should have to divert
- circling approach: you program the other direction while in the primary is the IFR part
- TO: you are not sure yet which runway you get
...

Ah, never thought about EO take off re-routing. Again, there are published procedures? I thought ATC would advise rather than wanting to fly an LNAV path with 1 engine... :bored:

Thank you both and good luck E.A.T on your transitioning. :D

All very good uses for the secondary flight plan.

Other two common ones are for circling approach, where we have the full instrument approach, plus the break off to a downwind position in the primary, and just the actual landing runway in the secondary. Also if in mountainous areas and you have specific oxygen escape routes, then I normally put these in the secondary. In the very unlikely event of a pressurisation failure then there's one less thing to think about in what is going to be a very hectic time.

Basically it's very useful for various what if scenarios, to help take the workload off you when you get a sudden change of plan.

Thank you for your input. I'll try it all out in the PMDG simulator now!

no problem, in most cases you are spot on and level here with this.

when it comes to rte2 : at scheduled airline operations with repeating flights the route is mostly stored in the fmc database and not put in manually every time . there maybe several possible routings to destination and due to e.g jetstreams the ops may decide which routing is optimum and so filed in the flightplan and tells you what routing you should select in the fmc.

it has little in common with unknown runways at departure/ arrival since at departure you should get the expected runway with your departure clearance at startup, when at arrival the runway and type of approach is still unknown you should nevertheless have to brief the approach when you finally get the information what you expect- selecting a pre stored runway then in the fmc is a thing of seconds and not an issue.

best regards

Appreciate your responses in both this thread and the ETP one. :ok: