Hello all, I have a question regarding real-world ATC IFR flights. Once you have the flight plan programmed and you're ready to go, and once you're in-air, if you see the flight path deviating away from the plotted flight plan, can you adjust to adhere to the plan or do you absolutely need ATC to authorise the adjustments?  

Here's a discussion of this issue (you can find more by searching the Internet):

http://www.avsim.com/topic/45448-atc-giving-you-resume-own-navigation-means/

 

Basically, you must follow ATC instructions for altitude and vectors. If they tell you to "resume own navigation" you must continue to follow your flight plan. If you begin to deviate you must correct and remain on that flight plan. You can either request an altitude change or cancel your IFR flight plan.

 

There are ATC controllers who post here, so one will correct me if I'm wrong.

Hi Mario,

 

Yep - any deviation needs to be approved by ATC - ATC is providing you a "clearance" to operate in the assigned airspace which allows them to maintain proper spacing... That said - many times ATC might have you deviate from your plotted flight plan - sometimes they may give you a "Direct To" to shave miles off your route (which benefits you) - other routine deviations are for traffic or weather... You need to follow ATC's assigned routing even if it differs from the flight path setup in your navigation equipment...

 

Regards,

Scott

 

 

if you see the flight path deviating away from the plotted flight plan, can you adjust to adhere to the plan or do you absolutely need ATC to authorise the adjustments?

 

I think you could keep this priority order in mind:

 

1. Always do what ATC tells you, no matter if they follows your plan or not.

2. If ATC says nothing, follow the filed flightplan.

3. If you do deviate from it ATC will contact you and tell you to get back on course so you'd better stay ahead of them and correct your course to follow the flightplan: no need to ask ATC for this correction because they expect you to do this if needed.

4. If you want to deviate yourself, ask permission form ATC. 

Great advice guys! Thanks!

The general idea of ATC is that they are your "eyes in the sky". They see more traffic than you do, so make sure you follow their advice as good as you can. Any deviation may cause a conflict that you may not be able to anticipate, so stick to your plan and communicate with ATC if you notice a deviation.

 

There is an exception, though: the pilot is ultimately responsible for the safe operation of the plane, so if ATC gives you an instruction that would compromise the safety of your flight, you should not follow that and advise ATC about this. For instance, Vatsim ATC once advised me to descend into the mountains. I told him I wasn't able to comply and he immediately corrected his instructions.

 

Peter

 

 

1. Always do what ATC tells you, no matter if they follows your plan or not

 

The pilot has the final say as in "UNABLE."

 

blaustern

The main purpose of ATC is to separate IFR traffic. You can deviate on any ATC instructions if you  consider them unsafe (ex TCAS traffic avoidance). However, you may be held responsible for your deviation unless you can provide good explanation for it.

 

 Most ATC controllers are friendly, and very good professionals. They will work  to accommodate your desired route if they can. 

 

 

You can deviate on any ATC instructions if you consider them unsafe (ex TCAS traffic avoidance). However, you may be held responsible for your deviation unless you can provide good explanation for it.

 

I must comply with all "RAs" which includes disconnecting the autopilot, autothrottle and maneuvering accordingly.  To not do so is a CRM.

 

There is a big difference between deviating and not telling ATC, and saying "Unable."  :smile: 

 

blaustern

I must comply with all "RAs" which includes disconnecting the autopilot, autothrottle and maneuvering accordingly.  To not do so is a CRM.

 

There is a big difference between deviating and not telling ATC, and saying "Unable."  :smile:

 

blaustern

 

I didn't write anything about deviating without notifying ATC. 

FAR 91.123 states you can deviate if you have an emergency, and notify controller as soon as possible. I'm not sure if "unable" will be sufficient magic-words-excuse in certain circumstances.

However, I did witness  on several occasions deviations from ATC instructions due to traffic avoidance when pilots notified ATC in very short sentences  "TCAS descent" or" TCAS climb"    

An inserting discussion and relevant to my IFR flight last night into YBBN where ATC vectored me for the ILS 01 approach.

 

Unfortunately holding the assigned course led me straight into a thunderstorm in my A2A 182 which overstressed the airframe (I have everything set to maximum realism) which ended the flight. Using AS16 and Rex Soft Clouds the lightning effects were incredible and realistically simulated the stress of flying into driving rain and thunderstorms at night. I got quite the shock when the overstressed dialogue popped up and ended the flight.

 

While it's possible to request an altitude change I can't see any way to request a course change with the standard P3D ATC unless I'm missing something obvious?

 

 

unless I'm missing something obvious?

 

The obvious is the default ATC is absolutely brain-dead.  Not even popular ATC addons detect storm cells as far as I am aware..., but I've been wrong on many things. The art of ATC is simply too difficult for an AI simulator that won't eat up your system resources and cost a ton of gold.

Your pre-planned flight plan is meaningless. Whatever clearance you get is the flight plan and it's very typical for ATC to give you something totally different than you filed.

 

It depends on where you are. When I was flying in the NE US, I rarely got exactly what I filed. In the Southern US, they basically just clear you direct everywhere though, so that's what I file usually.

 

 

You can deviate on any ATC instructions if you consider them unsafe (ex TCAS traffic avoidance). However, you may be held responsible for your deviation unless you can provide good explanation for it

 

TCAS, Weather and Terrain are the normal reasons we deviate, but normally prior to or as you are deviating, we inform ATC.

 

 

 

I must comply with all "RAs" which includes disconnecting the autopilot, autothrottle and maneuvering accordingly. To not do so is a CRM.

 

Not 100% so. The AFM states "Always follow an RA unless in the judgment of the pilot that doing so would be unsafe". Though 99.9% of the time you follow the RA, there are rare instances where you may not want to follow it. Also, TCAS was designed with the thought of flight attendants walking around pushing serving carts and passengers standing. The vert speed wheel is the preferred method of responding to an RA. I've had plenty RAs and I've never disconnected the AP or throttles while responding. I just spin the vert speed wheel up or down to until the VVI needle enters the fly to green area of the RA. Remember that TCAS warnings are progressive and have a time period instead of instant death.

 

When I was in the Air Force flying KC10s, I remember when we received our first modified jet. We were all trained on TCAS a year before the first modded jet returned. When guys started flying the modded jets, there was a lot of confusion with TCAS because of this. A few of the guys were treating TCAS RAs like a GPWS terrain warning. 2 crews actually seized the horizontal stabilizers on 2 of our jets while responding to RAs. One jet was bad enough that it had to land in the salt flats at Edwards AFB. After that, everyone had to be retrained and re-iterated to keep the AP on and use vert speed.