What is 'The Groove'

[flyco]

I have read various views about ' being in the groove', including statements like 'the groove should take between 17 and 28 seconds'. As a one-time professional pilot and a mathematician, I am having problems reconciling this well-meant advice - and I suspect many others are also.

 

I would, therefore, welcome some useful views on what is meant by the 'groove'. I understood it to from 'aligned with the landing deck centreline at 350 ft asl' and touchdown. Let me run through some simple maths to see if I can try and explain my problem.

 

For simplicity, take the deck height as 40 ft asl, and the point to aim for at the start of the groove as 3/4nm from touchdown and 340 ft asl.

 

At light weights the aircraft on finals will fly at around 125-130 kias, while the ship is typically doing 25-30 kts.

 

So the effective approach speed with respect to the ship is around 100 kts (or 0.277 nm per sec)

 

Hence to cover the 3/4 nm will take around 27 secs.- which I would see as the time 'in the groove'.

 

I really would welcome views on my above ponderings.

[Mav_CVW-66]

basically its just a term for the final approach aka the ball flying part of the approach

 

and the range from 17-28 secs is just because you will not always do your final Turn at exact the same Moment plus the diffrent wind speeds and dirrections

[David OC]

You will be closer in the groove at times, if your too long, you could mess up your wing / the guy behind you groove and he would be waved off. There is only around 45sec spacing, starts at the break with 10 second intervals.

[MooneyTail]

While your definition of the groove is mostly correct, I'm not sure where you got your numbers. During case I or II, you should be in the groove for 15-18 seconds. During Case III it will be from roughly 3/4 Mile to touchdown, however long that takes.

 

If you start falling outside of 15-18 seconds, the LSOs start to note it in your pass comments as they have someone who will actually time everyone's groove length.

 

For example, if you were 19 seconds, you will earn a (LIG) (that's read as "little Long In the Groove) tagged onto your pass comments. Given that that is in parentheses, it is a little deviation and you can still get graded an OK.

 

If you were on the opposite end, and only had 10 seconds in the groove, you would get a NESA (Not Enough Straight Away) and since it is a full deviation, no matter how good the pass is, the best grade you can get is a Fair.

 

It should be noted that the severity of deviations are in 3 second increments. Hopefully I didn't make that too confusing.

[flyco]

MooneyTail, your reply shows where my confusion arises.

 

You seem to be saying that the 'groove' does not extend from the 350 ft point to touchdown. As I hope I showed, that must take around 25-30 seconds. If I am only allowed 17 seconds that means it starts at a range of less than 1/2 nm, at which point, I would expect to be at less than 250 ft asl.

 

If I am going to ensure that I am not 'in the groove' for longer than 18 seconds, how do I do that. In effect 'What is the groove?' - I need a definition, and there does not appear to be an agreed one.

[Victory205]

I have read various views about ' being in the groove', including statements like 'the groove should take between 17 and 28 seconds'. As a one-time professional pilot and a mathematician, I am having problems reconciling this well-meant advice - and I suspect many others are also.

 

I would, therefore, welcome some useful views on what is meant by the 'groove'. I understood it to from 'aligned with the landing deck centreline at 350 ft asl' and touchdown. Let me run through some simple maths to see if I can try and explain my problem.

 

...

 

Simple. The Groove is where the LSO gets to yell at you without repercussion.

 

There is no real definition in LSO NATOPS, but the understanding is when the aircraft rolls wings level to touchdown. This is referenced as a given that was ordained by God before He allowed man to discover manned flight in most Naval Aviation references. Case III would be essentially when the pilot calls the ball to touchdown, around 3/4 of a mile or a little inside if the frequency is busy.

 

It's one of those things that really needs no definition, like the civilian term "short final". No one seems to know where to find the definition of that, yet no one cares because everyone knows what it means practically.

 

FWIW, the LSO is responsible for controlling the aircraft from the 180 to touchdown in Case III operations, 3/4 of a mile on a precision approach, or "paddles contact call" if the weather is crap, and the LSO needs to fix a bad start. That makes sense, because once an LSO makes that call, the expectation of the pilot is to follow the LSO's calls.

 

There are also many references to "being in the groove" that have to do with activities that take place while on liberty, but those are not appropriate for this discussion.

Edited August 4, 2018 by Victory205

[WarrenSkip]

The groove starts at about 3/4th a mile from when you're at the start coming out of the turn at the 180. Groove length should be 15-18 seconds TOPS, no less, no more. Not sure how you came to the conclusion that anything more than half a mile would equal to 20+ secs in the groove because I have done it.

Here's the video, graded by a USN pilot:

Long in groove by about 2 seconds.

https://i.imgur.com/PVpTvWW.png

[flyco]

OK, it looks as though I may have to succumb to the inevitable, although, as a long term pedantic 75yr old, I do take exception to be told that I am outside limits, but not being told what those limits are. But that’s the Navy for you.

 

If I am in the groove from whenever I roll wings level, then, by definition, if I roll out at 10nm I am in the groove from then on.

 

I suspect, having just reviewed Jabbers excellent tutorial, that I am using the wrong wings-level point. My understanding was that it was at 3/4 nm and 350ft. I will, henceforth, try for 250ft and 1/2 nm which should give me a time in the groove of around 18secs.

[WarrenSkip]

No flyco, Jabbers tutorial is correct. Wings level is at around .8nm at around 320-350ft. Rolling out at 10nm in a Case III recovery does not count as the groove.

[Heater741]

“Wave off!!!”

[MooneyTail]

Sorry for the confusion. 350 ft should be the altitude checkpoint at the 45 or when you're about crossing the wake. The groove doesn't start until you are wings level on the LAs extended center line, though.

 

Altitude checkpoints:

600' at the 180

450' at the 90

325-375' at the 45

Probably around 270' or so for when you actually roll wings level in the groove.

 

3/4 mile is not a checkpoint for Case I or II. It is where the ball call is made on a Case III.

Edited August 4, 2018 by MooneyTail

[Victory205]

There is a difference in apparent Glideslope and geometric Glideslope (Basic Angle) due to ship's movement and or wind. This angle must keep the actual aircraft descent rate within structural limits for a safe landing since there is no flare.

 

For example. The ship's normal Basic Angle is 3.5 degrees, but this results in an Effective GS angle of slightly less than 3 degrees, which requires a descent rate mimicking a no-wind, 3 degree GS for a typical approach speed. In high winds, the boat will go to a Basic Angle of 4 degrees, since a lower approach closure will result, changing the effective angle. So a 4 degree Basic Angle results in a GS of close to 3 degrees, putting the corresponding descent rate back where it needs to be. This is what is screwing up your public math...

 

The ball by the way, reacts quicker to power inputs when the winds are high.

 

3/4 of a mile constitutes a straight in reference, it doesn't indicate the distance where you roll wings level in the VFR pattern.

 

Hook to eye is another kettle of fish that few consider. It used to be a bigger deal when the ship had a spectrum of aircraft aboard. Now with Bumblebees, Hummers and "Q" A-6's, it's less of an issue.

 

The entire lens "plane of light" is tilted to put the proper GS on centerline to assure a minimum "hook to eye" distance as the aircraft crosses the ramp. So for an F14, if you saw a centered ball at the 45, you were low- if you were right of centerline with a centered ball, you were actually high.

 

An A7 required a level light plane, so they saw a true ball no matter where they were located from the centerline. I don't know what the value is for the Hornet. It all depends upon the hook (lowest point of the aircraft on approach) to eye (the "sensor" that tracks the optical glideslope) distance.

Edited August 4, 2018 by Victory205

[Talonx1]

I think an estimate of 125 kts is on the low side and 30 kts for the carrier is way on the high side. More reaistic would be 135kts and 25kts. That puts you much closer to proper groove time and if I’m not mistaken your groove clock stops on “in close” not in the wires so that shaves a little time off as well putting you closer to that 15-18 second mark.

[LORD FLASHEART]

Being too long in the groove will cause you to be cut off by guys flying correct pattern and will cause fights amongst pilots faster than anything. At VFA-113 you don’t even get to land if you’re long in the groove, we wave you off to clear the pattern for the guys flying it properly.

 

Long In the Groove effect on pattern explained at 8:40 approx:

 

https://youtu.be/BbMw4PcvMyY?t=8m36s

 

BbMw4PcvMyY?t=8m36s

Edited August 5, 2018 by JAR VFA-113 STINGERS

[MooneyTail]

That puts you much closer to proper groove time and if I’m not mistaken your groove clock stops on “in close” not in the wires

 

Unfortunately, you are mistaken. It is timed from wings level to touchdown.

[Talonx1]

Unfortunately, you are mistaken. It is timed from wings level to touchdown.

 

So be it, just thinking of grading stopping at close in perhaps.

Edited August 5, 2018 by Talonx1

[ttaylor0024]

So be it, grading stops at close in however.

 

That's not true either

[Talonx1]

That's not true either

 

To all I’ve read it is.

[ttaylor0024]

To all I’ve read it is.

 

As in you've read the virtual LSO stuff? IRL there's comments for at the ramp, to land, in the wires, and over the wires

[Talonx1]

As in you've read the virtual LSO stuff? IRL there's comments for at the ramp, to land, in the wires, and over the wires

 

True, I’m most likely thinking of virtual procedures. IRL it may not be the same and may not therefore effect groove time. Just trying to help explain why the math doesnt look right, because in fact it doesnt. By math alone a 15-18 second groove time would have you calling the ball much closer than 3/4 mile unless you are still in turn when you make the call.

[ttaylor0024]

True, I’m most likely thinking of virtual procedures. IRL it may not be the same and may not therefore effect groove time. Just trying to help explain why the math doesnt look right, because in fact it doesnt. By math alone a 15-18 second groove time would have you calling the ball much closer than 3/4 mile unless you are still in turn when you make the call.

 

3/4 mile isn't a thing in case I or II, that's just from the movies. It is just whatever it takes to get 15-18s, don't really do any math, just use experience and gouge.

[Talonx1]

3/4 mile isn't a thing in case I or II, that's just from the movies. It is just whatever it takes to get 15-18s, don't really do any math, just use experience and gouge.

 

Fair enough.

 

https://www.cnatra.navy.mil/local/docs/pat-pubs/P-1211.pdf

 

T-45 but worth a read for anyone with pattern questions.

[LORD FLASHEART]

“IN CLOSE” is where VFA-113 box grading stops. We have numerous deviations after “IN CLOSE” that we grade on.

 

15-18 seconds is what our LSO mission aims at with the “3/4 mile” ball call. In real life it’s mostly zip lip however this makes for boring PLAT videos. We also use the ball call stuff to standardise everyone’s grading.

I recall the F-14 NATOPS says you intercept glideslope at 0.6nm. Our “3/4 mile” call happens just after this so you’re calling the ball at around 0.5nm. “3/4 mile” isn’t meant to literally mean 0.75nm - it’s just a fun voice for interactivity with the ship.

 

But yeah, 15-18 seconds is what our SMEs have always pushed for in VFA-113.

[Nealius]

Resurrecting this discussion because I'm trying to learn how to time my own groove times and I'm stumped. 

We've established that there's no set definition of the Groove. We've also established that the Groove more-or-less starts when you roll wings level, and the Jabbers tutorial says that is 0.8nm. We've also established that you do "whatever it takes" to get the proper groove time, however that is not a concrete goal for layman's practice, like the 0.8nm marker is. 

When I roll wings level at 0.7nm my Groove is 22 seconds when the boat is 23kts, 7kts natural wind. Is this because of the higher wind speed? To shave off 4 seconds I would most likely be wings level at, like one of the other posters mentioned, 0.5nm or less. 

[BarTzi]

1 hour ago, Nealius said:

the Jabbers tutorial says that is 0.8nm.

Where? Watching his video, he levels at 0.6-0.5NM