IFR flight plans with GPS direct

What are your experiences with planning IFR flight plans with GPS direct? Where in the country can you file direct and fly IFR? How do you deal with congested air traffic areas? And minimum altitudes? How often did your routing get changed? Recent experience with ATC on the west coast suggests that experiencs will vary!

Cheers
Rick

What are your experiences with planning IFR flight plans with GPS direct? Where in the country can you file direct and fly IFR? How do you deal with congested air traffic areas? And minimum altitudes? How often did your routing get changed? Recent experience with ATC on the west coast suggests that experiences will vary!

Rick,

In Southern California, the short answer is “forget it.” It’s pref routes all the time. I’ve had better luck when north of SoCal’s airspace, including being cleared direct to the initial fix for the approach into Oakland while still over Paso Robles. In the intermountain West and Midwest it’s ben quite easy to get direct clearances to distant fixes.

I must confess that we’ve been filing airways, then asking for “direct to” shortcuts once aloft. We’ve not been given any unexpected altitude changes.

Cheers,
Roger

In the St. Louis area, we get GPS direct routinely. As a matter of fact, if I file for the airways to get VOR tracking practice, they often ask me if I want GPS direct.

Andy

The columns by Don Brown on Avweb (the “Say Again” series) are well worth reading to find out what the controller’s perspective is on this kind of thing. In particular, his #2 column “The GPS Mess” touches on the problem with GPS direct; the boundaries of ATC sectors were drawn to accomodate the airways - if you plan a direct route, you are likely to cross more sector boundaries, and indeed might pass very close to points where three or more sectors meet. This makes it hard for the FAA computer to get the right information to the sector controllers you will actually end up talking to. Read the article for more explanations and tips.

Rick: My experience is similar to Roger’s. I always file airways and then ask for direct enroute.

Sometimes you will get the direct clearance to the destination and sometimes only to an intermediate fix.

One controller said they “were having problems with” direct clearances in the San Joaquin Valley northbound.

It seems to me that the F.A.A. computer is set up for airway routes but it doesn’t hurt for a direct clearance if the frequency is not busy.

One thing to consider with GPS direct is terrain clearance. Unless you are in a location where the terrain is pretty flat you had better make sure what the terrain is before you charge off the airways. Coming up from Southern California I wouldn’t even consider GPS direct until out over the San Joaquin Valley.
Sure you can see the terrain display on the Avidyene or ARNAV but suppose the internal computer on that unit goes belly up during the flight.

On the flight out to California from KDLH to KRAP my CFII and I had been flying for a long while already and left right about dusk. I asked for “direct Rapid
City” and Duluth Departure didn’t even hesitate before approving the amended clearance. The ensuing flight was kind of dull though, with neither the heading or altitude varying for the next 500 n.m. or so all the way to Rapid City.

Regarding direct routes - forget it in the NE. You almost always will get airways. If you want to maximize the chance of direct be sure that direct doesn’t pass through any Class B airspace enroute (actually at least 5000 feet above any Class B). If you’re going to a busy area another trick is to file to an approach gate. Even if your destination airport doesn’t have a terminal arrival route see if a nearby busy airport does. For example if you’re going to any airport in the Chicago Area you will be routed either over OBK, FARMM, BDF or JOT. When you depart Chicago your first fix will be BAE, SIMNN, GIJ, EON or ELX. You can find these by looking at the ORD arrivals and departures. Similarly you can check any busy area and see what fixes are used for arrivals and what are used for departures. Filing those fixes will minimize the chance of a routing change. Also, understand that while your original clearance may specify direct, as you change airspace boundries, especially as you near the destination, the routing may change due to local requirements. Knowing the local requirements in advance is very helpful.
The most important thing is what was mentioned by several others. If you’re not over very low, flat terrain be sure that your direct route provides you with sufficient obstacle clearance.
One more tip is that if your route passes through several centers you can make life easier by including a fix in each centers airspace. This can be a VOR that’s essentially on the direct route or a LAT/LONG. It makes it easier for the computer and for the controllers to coordinate. Finally, if you’re sure you have terrain clearance ask for direct. The worst that can happen is that the controller will say “unable”.

I have ALWAYS gotten GPS direct from one airport to another as my initial clearance when I filed it that way. I’ve had a few re-routes once airborne, but most of them only pointed me to a nearby VOR. As soon as I got near that VOR, I got re-routed back to my “direct-to” clearance. The only major exception was today. I filed direct HKY-LZU. Initial clearance was “as filed”. Once airborne, I got a re-route “Direct SUG, direct ODK, Awson 1 arrival, LZU”. SUG and ODK are VORs that are almost in-line with a “direct-to” routing (1% longer according to DUATS), so when I reached SUG, I asked for “direct LZU”. ATL center told me traffic was so heavy, they needed me on the AWSON 1 arrival for sequencing. When I got to ODK, I was cleared direct LZU, as traffic had died down significantly (It was a very weather active day in the SE today). My longest GPS “direct” was Owensboro, KY (OWB) to Fort Lauderdale (FLL) with no re-routes at all (made for a boring ride, actually, so we stopped at Macon, GA (MCN) and Ocala, FL just to break it up).

Rick,
The GNS430 has a ‘minimum safe altitude’ function you can use for a direct to route. I believe it is a selectable field you can put on NAV page 1. There is also an ‘enroute safe altitude’ you can use. The only place I have found these two features mentioned is in the glossary where the terms are defined. They may be discussed in the handbook somewhere, but I have not found it. I think this is a subject that is overlooked and deserves more attention. I recently had an instrument flight check and the examiner quizzed me on all of the MEAs, MOCAs, MCAs, etc. on the low level enroute charts, but never asked the first question about how to determine if a direct to route provides adequate clearances. I also found the FAA not really ‘with it’ in general when it comes to GPS usage and exactly when it can be used in substitution for ground based navaids. It appears that GPS technology has far outpaced the regs.

Hi Rick: although everyone has answered these questions, I’d thought I’d add my cents.

Q. What are your experiences with planning IFR flight plans with GPS direct?
A. I plan all of my IFR flights Direct. Unless weather or icing require me goint a different direction or altitude.

Q. Where in the country can you file direct and fly IFR? How do you deal with congested air traffic areas?
A. I do it everywhere. As was stated the Northeast is difficult. But only within the terminal areas. I fly out of the DC area (HEF) and will never actually get direct. However, I’ve found through experience, that by filing direct, the controller more often gives me shortcuts when they are able without me asking. If I have to ask the answer is usually no, otherwise they would have given it to me already.

Also, when flying back to DC I will get Direct, but the routing will be changed to a STAR (from the west or south) and airways and fixes (from the east). This is usually no problem since I can fly the majority of my route direct. Remember though the controller is usually going to ask “on course heading.” Also be aware that flying through restricted areas, may not be noticed until you get closer to them. While of course, they have to get you around, on more than one occassion I’ve suggested a better vector that will keep me clear. Also sometimes you can change altitudes and be clear of the area as long as they don’t mind. This sometimes can be shorter than a large vector.

Q. How do you deal with congested air traffic areas?
A. If it’s a problem, they’ll change your routing.

Q. How often did your routing get changed?
A. In the DC area, my routing gets changed more often than it doesn’t. GPS had little effect on this. I got my routing changed all the time without it.

Derek

My west coast experience square’s with Roger’s: file pref routes or airways, then ask for direct to navaid, intersection, fix, or destination once airborne. There’s a good chance you’ll get it, unless it sends you right through the approach path to LAX or SFO!

Stephen, that was my experience also – getting direct clearances was easy in the midwest and nearly impossible in the west. Only in the San Joaquin and Salinas valleys has ATC provided shortcuts.

Appreciate the need to be concerned with terrain clearance. Best quote from a friend in search and rescue – “look for the highest peak along a GPS direct route and begin searching there.” Ouch!

Cheers
Rick

It has been my experience that the more congested the airspace, the less likely you are to get ‘direct’ clearances. For instance, southern FL, Atlanta, Orlando, DC and the Chicago area are difficult. Don’t even think about it in the Northeast!

I have found that filing VOR to VOR as long as they are not more than 10 miles off route gives the ATC a method to understand where you are and doesn’t add too much time. Then I will ask for direct to the next waypoint. Regardless, of what clearances I am given, when I get close to intense Class Bs, I get rerouted.

After one or two trips through a class B where I get the same reroute, I just learn to expect it. No use fighting it.

Marty

In reply to:


Don’t even think about it in the Northeast!


I agree. The IFR route I’ve flown most frequently recently is the DC area to the Boston area – GAI to BED. When it’s VFR, it’s possible to do this in a nearly direct routing. KGAI->SAX (the “Sparta” VOR) -> KBED stays just outside the New York Class B nightmare, and is only 2nm longer than a direct flight. That’s what I fly whenever weather permits.

I’ve learned that if I have to go IFR, it will be a convoluted airways route, along V93 for the first two thirds of the trip, that adds about 50 miles to the total distance. But that is how I am going to be cleared no matter what I file. And I’ve had very limited success asking for shortcuts enroute – perhaps because the air space is under several jurisdictions. (Much of the flight is under the supervision of Reading approach or Allentown approach etc and they seem reluctant to offer much more than a few-mile shortcut along the airway.)

Another reason to live in Duluth!

Interesting RE Atlanta area comment: Not to say you’re wrong across the board, but I regularly get “direct” routing into, out of, and through the Atlanta class B airspace. Of course, I also do my homework before filing, and file for an altitude that is at least 1000 ft above the highest MOCA for my route. I also use direct routing end points of my own choice that keep me from getting too close to Hartsfield airport ( I don’t mind a self-imposed jog to the left or right as long as I don’t get vectored or re-routed to BFE by ATC). I also try to hit the ATL class B at non-push times…that really helps!

One more thing I forgot to mention in my previous post. If you can, go high and try to stay in center airspace. Low altitude flights tend to pass through a number of approach control juristictions and it requires much more coordination to get a direct routing. East of the rockies 11,000 feet will almost always do it although many class B area approach controls go up to 13,000. But anyway, the higher the better.

Bill,
I also fly in the Southeast and I almost always receive the ‘Direct To’ clearances I request. I was also flying around all of the T-storms in the area yesterday and filed out of Nashville direct Chattanooga direct Greenville-Spartanburg direct Rock Hill to loop around a bunch of weather. They also accomodated my frequent deviations and altitude requests almost without exception, and they were busy. I think there is just more airspace per plane in this area and it isn’t so much of a problem. By the way, Bill, I think I heard you on a frequency yesterday afternoon repeating your call sign and aircraft type a couple of times. I’ll be glad when these guys learn to listen for the subtle difference between a Cirrus and a Sierra. I finally had to spell Cirrus out for a guy the other day that kept referring to me as “Sierra one one mike zulu”. Normally I would have just let it go, but the speed difference between the two planes may have caught him by surprise at an inopportune time.

LOL - Yes, it may be the way I speak, but I’m frequently referred to as a Cessna, Sierra, etc. I too, heard a couple of Cirri on the air yesterday - one while I was talking to Ashville Approach, and another on Greer Approach. Perhaps one of them was you, but I was too busy dealing with the bumps to keep track of the call signs…! The funniest thing was coming home to HKY last night at about 8 pm – I shot the slot between the two convective sigmets – (it was an amazingly smooth ride in clear air. Even though the Macon FSS repeatedly advised me not to launch, the view out the window just didn’t match what he was saying, so I decided to poke my nose into the weather instead of laying over, with the option of doing a 180 if it looked like he was correct after all. He was SO wrong! and so it goes…)

So, for the funny: I got handed off to Greer approach at about 8:30 pm. There was only me, a C210 heading to Columbia, SC, and the controller on freq. The conversation went something like this:

Greer Apch:“Citation 508JS, radar contact 14 miles south of GMU.”
Me: “Greer, correction, 508JS is a Cirrus, not a Citation”
Greer Apch: “roger”
Greer Apch: (after about a minute of silence) "Cirrus 8JS, Do you know what the winds at your altitude are?
Me: “Macon radio said 270 at 75, but I haven’t checked with the GPS”
Greer Apch “8JS, Well, I show you at 35 hundred feet, heading 045 at 220 knots. As far as handling
in my airspace is concerned, you can pretend to be a Citation tonight!”

I like to have MSA (Minimum Safe Altitude) and ESA (Enroute Safe Altitude) in the data fields on the map page (NAV page 2) of my #2 GPS. It is easy to change the data fields by hitting menu when you are on the map page. The definitions are in the user manual.

Yep, one of those other Cirri was me. Same arrival time to Rock Hill, SC, same bumps, and apparently the same FSS briefer out of Macon. I talked to him enroute and you would have thought I was about to penetrate a hurricane. The unfortunate thing about this is that they are so overly cautious that the value of a weather briefing has dropped to the point I only halfway listen to them. After all of the tales of horror, I made an easy visual approach under 9,000’ ceilings.

I also fly out of the DC area. My experience was to file direct EVERYWHERE, because I would get a different departure no matter what I filed and would usually get direct as soon as I got out of DC, regardless of what I filed. It seems ATC is now understanding what “slant golf” after your airplane type means, and is getting very comfy giving direct to pilots with GPS, whether or not they ask for it. Truly, if I want to fly VOR’s for some bizarre reason, I usually end up rejecting ATC’s offer to send me direct.

The new DC TFR’s have complicated this, since my airport is within the TFR (CGS). If possible, I try to file VFR into my home airport. That way I can get within 8 miles before picking up ATC. If I go IFR into my airport, ATC sometimes sends me to Frederick, Md fist…about 40-50 miles out of the way!