When Able

[RMCN172RG]

Some how I missed the meanig of this aviation term in my IFR training.

Taking the ASF IFR Insights course on the internet I now know what it means and how my interpetation could have had serious consequences.

Background, PPL OCT 2006, IFR Training completed MAR 2007. First IMC-IFR cross country JUL 2007 ~120 hour total time. Second IMC-IFR cross country APR 2008. Both cross coutries were from MYR to PHN. In July we had the typical summer T-Storm flare-up to worry about. In April I was crossing the mountains at 6000 in light rain with the freezing level at 8000 keeping me from going higher.

ATC -"216JA turn heading 300 direct Briggs WHEN ABLE".

I interpet since Briggs is not on the flight plan that ATC has me turning west to pass behind a storm cell. Once I have determined a course to Briggs go direct. That will keep me clear of the weather.

What I now understand that ATC phrase to mean. Turn heading 300 when weather allows go direct to Briggs.

Similar circumstances in April except the VOR was on my flight plan.

I do not remeber the term "WHEN ABLE" being discussed with my CFI's or in the Cessna/King course.

I would appreciate some expert direction on determining what I should do when I am in IMC, cannot see the weather picture and get a When Able instruction?

Thanks

 

[ScottM]

I have always treated like 'pilot's' discretion'. IOW when I feel it is safe and prudent to do so, comply with the instruction.

 

[Teller1900]

Exactly what Scott said, but when in doubt of the weather outside or what a clearence means...ask 'em. If they give you an instruction that you think might put you into some heavy weather, ask them what they see on their scope, or ask then for vectors around it. Then ask them if you're clear before going direct again. They have weather radar, you I take it, don't. They can see what you can't. When in doubt, ask them.

On the flip side, if you can see out your window that the turn they just gave you is going to put you into some weather, ask to stay on course, or ask for a different turn to stay clear. If they give you a turn "when able," tell them you're going to stay on course for another X miles until clear of the dark clouds next to you; they might give you a better option to get around the weather that you can't see. If there's weather out there, they'll do everything they can to keep you out of it.

 

[bobmrg]

Some how I missed the meanig of this aviation term in my IFR training.

Taking the ASF IFR Insights course on the internet I now know what it means and how my interpetation could have had serious consequences.

Background, PPL OCT 2006, IFR Training completed MAR 2007. First IMC-IFR cross country JUL 2007 ~120 hour total time. Second IMC-IFR cross country APR 2008. Both cross coutries were from MYR to PHN. In July we had the typical summer T-Storm flare-up to worry about. In April I was crossing the mountains at 6000 in light rain with the freezing level at 8000 keeping me from going higher.

ATC -"216JA turn heading 300 direct Briggs WHEN ABLE".

I interpet since Briggs is not on the flight plan that ATC has me turning west to pass behind a storm cell. Once I have determined a course to Briggs go direct. That will keep me clear of the weather.

What I now understand that ATC phrase to mean. Turn heading 300 when weather allows go direct to Briggs.

Similar circumstances in April except the VOR was on my flight plan.

I do not remeber the term "WHEN ABLE" being discussed with my CFI's or in the Cessna/King course.

I would appreciate some expert direction on determining what I should do when I am in IMC, cannot see the weather picture and get a When Able instruction?

Thanks

"When able" usually refers to terrain features, not weather, but if Center's WARP display shows a big boomer that might be an occasion to use it. There is quite a long delay (as long as 11 minutes) between real-time and when something shows up on a Center scope, so it may be that the controller is hoping that you have better information than s/he does.

Of course, reading the definition in the Pilot/Controller Glossary helps...don't depend on what you were fed during your training to answer all of your questions.

Bob Gardner

Bob Gardner

 

[bobmrg]

Exactly what Scott said, but when in doubt of the weather outside or what a clearence means...ask 'em. If they give you an instruction that you think might put you into some heavy weather, ask them what they see on their scope, or ask then for vectors around it. Then ask them if you're clear before going direct again. They have weather radar, you I take it, don't. They can see what you can't. When in doubt, ask them.

On the flip side, if you can see out your window that the turn they just gave you is going to put you into some weather, ask to stay on course, or ask for a different turn to stay clear. If they give you a turn "when able," tell them you're going to stay on course for another X miles until clear of the dark clouds next to you; they might give you a better option to get around the weather that you can't see. If there's weather out there, they'll do everything they can to keep you out of it.

A common controller complaint at the annual "Communicating for Safety" conferences is the delay in displaying weather. At the last one I attended, they had a slide show of a fatal accident where the controller had issued a vector based on what he saw on the scope, not realizing that the echo had moved several miles...he ran the pilot right into the middle of it.

They do their best, given the limitations of the equipment.

Bob Gardner

 

[MauleSkinner]

ATC -"216JA turn heading 300 direct Briggs WHEN ABLE".

I interpet since Briggs is not on the flight plan that ATC has me turning west to pass behind a storm cell. Once I have determined a course to Briggs go direct. That will keep me clear of the weather.

What I now understand that ATC phrase to mean. Turn heading 300 when weather allows go direct to Briggs.

I'd read that as "Turn to 300 degrees now. That's an approximate heading for Briggs. When you've got Briggs dialed in suitable for navigation, proceed direct."

As others have mentioned, ATC probably assumes, based on what they see, that this will keep you clear of the weather.

I'd also say that it appears to me you accepted a clearance to a fix that wasn't on your flight plan, and didn't verify the routing after that...make sure you and ATC are on the same page as to where you're going.

I would appreciate some expert direction on determining what I should do when I am in IMC, cannot see the weather picture and get a When Able instruction?

Thanks

I think this has more to do with not getting yourself in a situation where you're IMC with hazardous weather in the area and don't have access to on-board weather displays (radar, etc.), rather than what to do when you are in the situation. If you know about it ahead of time, don't go there. If it "pops up" while enroute, find a place to land and figure it out.

My 2cents.

Fly safe!

David

 

[Teller1900]

I'd read that as "Turn to 300 degrees now. That's an approximate heading for Briggs. When you've got Briggs dialed in suitable for navigation, proceed direct."

Ya I forgot to mention that...the direct part is "when able," the turn is now. If you don't like the turn, ask for something different, but his clearance involves a turn right now. You'll get that lot if you're /A...they'll clear you on a heading, direct the VOR when able.

They do their best, given the limitations of the equipment.

Absolutely. And as long as you know and recognize their limitations, I'd much rather have a controller with 12 minute old weather than no weather at all (assuming I managed to get myself into a bad spot to begin with). Even with the delay on their scopes, the controllers seem to have much better wx data than what our on-board radar can do a lot of them time, especially with embedded cells or when we're in heavy rain or appreciable icing (when our radar becomes almost useless).

 

[Teller1900]

The terminology that ATC would use if they expected you to turn right then would be either "216JA turn heading 300 direct Briggs" or "216JA turn heading 300 direct Briggs Expedite".

'When Able' means exactly that. when you are able to turn.

I disagree, Scott. Maybe I'm just thinking about this wrong, but if they're giving you an option on the turn, wouldn't it be "When able, fly heading 300, direct Briggs"?

When it's given as "Fly heading 300, direct Briggs when able" I take that to mean fly the heading now, go direct when you can (when GPS is set up/VOR is suitable for naviation/etc). It's kind of like in the decent - "XXX descend to 10,000, then descend and maintain 6,000 at pilot's discression." They want you at 10, now, then 6 at your leisure.

 

[ScottM]

I disagree, Scott. Maybe I'm just thinking about this wrong, but if they're giving you an option on the turn, wouldn't it be "When able, fly heading 300, direct Briggs"?

Yeah, After I reread his note I removed my post. The lack of the comma in the first post lead me to think something else.

If the controller did say
"216JA turn heading 300 direct Briggs WHEN ABLE" that is different that 216JA turn heading 300, direct Briggs WHEN ABLE.

 

[Teller1900]

Yeah, After I reread his note I removed my post. The lack of the comma in the first post lead me to think something else.

If the controller did say
"216JA turn heading 300 direct Briggs WHEN ABLE" that is different that 216JA turn heading 300, direct Briggs WHEN ABLE.

Aren't semantics fun .

 

[sba55]

I disagree, Scott. Maybe I'm just thinking about this wrong, but if they're giving you an option on the turn, wouldn't it be "When able, fly heading 300, direct Briggs"?

When it's given as "Fly heading 300, direct Briggs when able" I take that to mean fly the heading now, go direct when you can (when GPS is set up/VOR is suitable for naviation/etc). It's kind of like in the decent - "XXX descend to 10,000, then descend and maintain 6,000 at pilot's discression." They want you at 10, now, then 6 at your leisure.

I agree - there's another very common case where this might be used, especially if you're /A. We get lots of headings, direct <some VOR> when able, usually when the VOR is far away. They are issuing a vector, though, so the turn happens right away.

As far as the original question goes - in addition to everything that's been said above, you could also be flying through an area where ATC doesn't have weather radar coverage. N Wyoming - N Nevada is such an area, for example. I have asked ATC for vectors around weather over the mountains there before, but there aren't enough ground stations for them to be able to see anything.

-Felix

 

[RMCN172RG]

I agree - there's another very common case where this might be used, especially if you're /A. We get lots of headings, direct <some VOR> when able, usually when the VOR is far away. They are issuing a vector, though, so the turn happens right away.

As far as the original question goes - in addition to everything that's been said above, you could also be flying through an area where ATC doesn't have weather radar coverage. N Wyoming - N Nevada is such an area, for example. I have asked ATC for vectors around weather over the mountains there before, but there aren't enough ground stations for them to be able to see anything.

All of the above is true in my case the plane is /A with VFR GPS and on one of the flights I was above MEA but below radar coverage. In that case ATC insured I was on the correct radial from VOR-A and would follow that until the correct radial to VOR-B and not going direct between the VOR's. I was and had the GPS setup with the intersection waypoint.

So the interpetation turn to heading 300 now. Then fly that heading until you are A) in range of the Briggs VOR then go direct or B) can set up the GPS direct to Briggs and fly that as soon as possible?

 

[flyingcheesehead]

Yeah, After I reread his note I removed my post. The lack of the comma in the first post lead me to think something else.

If the controller did say
"216JA turn heading 300 direct Briggs WHEN ABLE" that is different that 216JA turn heading 300, direct Briggs WHEN ABLE.

Huh???????

Let's look at that another way...

If the controller did say
"216JA turn heading 300 direct Briggs WHEN ABLE" that is different that
216JA turn heading 300, direct Briggs WHEN ABLE.

Those look the same except for the comma - Which means they ARE the same on the radio because the controllers don't say "comma." I don't think there's any way to read multiple meanings into that instruction.

"N1234X, turn left heading 300, direct Briggs when able" means "turn now, go direct Briggs when you can." (within service volume, no weather in the way, etc.)

The one we hear a lot around here is "SpamCan 123, fly runway heading, cleared for takeoff runway 18" followed by Departure giving them "Turn right heading 280, direct Nodine when able." Since Nodine is to the west-northwest, if the turn wasn't immediate the "when able" part would never happen (airplane is pointed south).

 

[poadeleted20]

We don't need no stinking semantics -- we have the P/CG:

WHEN ABLE- When used in conjunction with ATC instructions, gives the pilot the latitude to delay compliance until a condition or event has been reconciled. Unlike "pilot discretion," when instructions are prefaced "when able," the pilot is expected to seek the first opportunity to comply. Once a maneuver has been initiated, the pilot is expected to continue until the specifications of the instructions have been met. "When able," should not be used when expeditious compliance is required.

 

[ScottM]

We don't need no stinking semantics -- we have the P/CG:

Deals with "prefacing" instructions with the term. In this case the instruction is suffixed and can lead to miscommunication.

For instance is it turn now to 300 and then go direct Biggs when able to do so? Or is it turn to 300 and go direct Biggs when able to comply with both instructions?

Sounds like the proper phrase would be either be;

When able, turn 300 and direct Biggs or Turn 300 and when able direct Biggs.

 

[Greg Bockelman]

When able, turn 300 and direct Biggs or Turn 300 and when able direct Biggs.

The turn is now. The direct is when able. That is just the way it is. It always means the later, never the former.

 

[t0r0nad0]

So it's kind of like the METAR text for heavy or light precipitation - the part affected by the modifier depends on where the modifier is:

-RASN is Light Rain and Snow
RASN- is Rain and Light Snow

Likewise, "When able, turn left 300 direct Briggs" is make the turn whenever you're able, and then go direct Briggs, while, "Turn left 300, direct Briggs when able" means turn now, and go direct to Briggs whenever you're able.

Am I understanding this properly?

 

[poadeleted20]

You got it right, PJ, although I s'pose to be gnat's-butt book-correct, the controller should really have said, "Turn left 300, when able direct Briggs" so the "when able" was properly a preface, not improperly a suffix. And for the next person who accuses me of pedantry, I warn you all that I resemble that remark.

 

[SkyHog]

You got it right, PJ, although I s'pose to be gnat's-butt book-correct, the controller should really have said, "Turn left 300, when able direct Briggs" so the "when able" was properly a preface, not improperly a suffix. And for the next person who accuses me of pedantry, I warn you all that I resemble that remark.

Eek...couldn't that kind of be heard as "Turn left 300 when able. Direct Briggs" ?

 

[t0r0nad0]

My thoughts exactly, Nick. Thanks for the clarification Ron.

 

[SkyHog]

My thoughts exactly, Nick. Thanks for the clarification Ron.

I'm thinking: "Turn left 300. Oh, by the way, when able, direct briggs."
LOL

 

[gprellwitz]

I'm thinking: "Turn left 300. Oh, by the way, when able, direct briggs."
LOL

Actually, to reduce (eliminate?) confusion and keep it short, "turn left 300 and when able direct briggs." Ron, thanks for that post. I was going to say the same thing, but didn't want to be accused of pedantry.

pedantry, n.


1. The character, habit of mind, or practice of a pedant.
a. Mere academic learning, without judgement or discrimination; excessive reverence for or display of learning or technical knowledge; intellectual conceit.
b. Excessive or undue concern for petty details; slavish adherence to formal precision, rules, or literal meaning.

 

[flyingcheesehead]

You got it right, PJ, although I s'pose to be gnat's-butt book-correct, the controller should really have said, "Turn left 300, when able direct Briggs" so the "when able" was properly a preface, not improperly a suffix. And for the next person who accuses me of pedantry, I warn you all that I resemble that remark.

I think this is why the "when able" is almost always used as a suffix in this context (two instructions):

Let's look at three of the examples given in this thread:

"Turn left 300 when able. Direct Briggs"

"Turn left 300, when able direct Briggs"

"Fly heading 300, direct Briggs when able"

The first two, you can't tell the difference between them - No punctuation (except "daycimal") in radio comms. The thing is, the two appear to have different intentions - turn when able, or direct when able?

I liken it to PJ's example:

-RASN is Light Rain and Snow
RASN- is Rain and Light Snow

The first two examples above would be analagous to "RA-SN" which makes no sense.

Finally, the instruction "Turn left heading 300 when able AND fly direct Briggs" (and added for clarity of intent: fly heading 300 when able, and go direct Briggs) makes no sense - Unless you're already on the 120 radial of Briggs flying 300, there is one and only one time where a heading of 300 is going to take you direct Briggs. So when you're able to make the turn, do you fly 300, or do you fly direct Briggs (which in this case is NOT modified with a "when able").

That is why "Fly heading 300, direct Briggs when able" will ALWAYS mean "fly 300 now, fly direct Briggs as soon as you can."

Also, WRT the P/CG, I don't read it as requiring the "When Able" to be a prefix. The part where it says prefix is simply an example, where it should probably say "as opposed to being prefixed with 'at pilot's discretion.'"

However, the 7110.65 gives the example as "FLY HEADING (degrees). WHEN ABLE, PROCEED DIRECT (name of fix)". And, that is the one and only usage of "When Able" that is used as an instruction in the 7110.65 - The rest are requests for pilots to report certain things 'when able', for example, for a weather deviation the controller may say "Deviation approved, advise when able to proceed direct <fix>."

 

[Everskyward]

Fly 300 now. Fly direct Briggs once you are; clear of the storms; receiving a nav signal; have figured out how to enter it into your FMS....

Usually if you are deviating for weather the pilot initiates the deviation (although the controller might suggest it). Once you ask, they may say something like "deviations right of course are approved" or they may give you some kind of restriction like, "no further right than 270 degrees." They will probably ask you to tell them when you are back on course. It's a good idea anyway.

If you are IMC without radar or a way to figure out where the storms are I would suggest asking ATC. Their radar is much better now than it was, say, 10 years ago. However, I wouldn't take this as a license to go off into an area of embedded thunderstorms without radar depending only on ATC.

 

[nosehair]

So, Ray, what we all can get from this is the old bottom line: Anytime you don't clearly understand and can comply with full knowledge of a clearance, ask. Ask the controller in no uncertain terms what he means.

This is a clear example of how a little word or phrase can cause confusion and no man is expected to understand every word or phrase all the time.

A clarification question is always the right thing to do.

 

[gkainz]

What Mari said!

 

[bobmrg]

Ya I forgot to mention that...the direct part is "when able," the turn is now. If you don't like the turn, ask for something different, but his clearance involves a turn right now. You'll get that lot if you're /A...they'll clear you on a heading, direct the VOR when able.



Absolutely. And as long as you know and recognize their limitations, I'd much rather have a controller with 12 minute old weather than no weather at all (assuming I managed to get myself into a bad spot to begin with). Even with the delay on their scopes, the controllers seem to have much better wx data than what our on-board radar can do a lot of them time, especially with embedded cells or when we're in heavy rain or appreciable icing (when our radar becomes almost useless).

Are you folks having trouble reading the definition in the P/C Glossary?:

"....gives the pilot latitude to delay compliance...."

Bob Gardner

 

[poadeleted20]

I think this is why the "when able" is almost always used as a suffix in this context

That may explain why controllers use it improperly, but it doesn't change the fact that the P/CG calls for it to be used to preface the instruction. If you've read the P/CG, you know that "when able" only applies to the following instruction. Make up your own alternate rules of construction at your own risk.

 

[Dave2]

Thank ya'll. EXCELLENT discussion.

 

[ApacheBob]

Are you folks having trouble reading the definition in the P/C Glossary?:

"....gives the pilot latitude to delay compliance...."

Bob Gardner

But not the longitude! How can you navigate without the lat/longs?
ApacheBob