How to lose time inflight

[Malc]

One for the mathematicians amongst us…

I am 15 miles from next steerpoint, but my ETA is one minute ahead of the planned TOS, so I need to lose a minute. Simple solution is pull the throttle back and slow down until the TOS caret is back in line but I don’t want to slow down as this will bring me into a speed range which is not tactically astute - I want to maintain 350 knots CAS.

If I decide to fly an offset of 45 degrees I can extend my flight path by 6.2 miles, which at 350 knots will take me 1:04 minutes extra on top of the original 2:34 minutes to cover, so I’ve lost my minute and arrive on time at the same desired speed. I need to fly 45 degrees perpendicular to my desired heading for 1:34 minutes, then turn 90 degrees back towards the original flight-plan for another 1:34 minutes. However, when I try this in the cockpit I am still ahead of the game.

Where am I going wrong? When I get back on track, I am still early…

[Dee-Jay]

If you are one min early, take 60° offset in one side, fly one mine, then take 120° on the other side, fly one minute, then resume track.

[Malc]

Yep, “60 for 60 then 120 to resume” sounds a whole lot easier than trying to remember than my sums! Thanks Dee-Jay.

[Morgan]

From Dee-jay

[Stevie]

Nice gouge, Dee-Jay!

[RhoBee]

FWIW back in the Jurassic age we planned and flew our low level missions at a GROUND speed that is a multiple of 60. We used a minimum GS of 420 knots, but typically 480 knots enroute then accelerate to 540 for the IP to target run. Why a multiple of 60? Well, all you have to do is divide your ground speed by 60 to calculate the nautical miles per minute. Using a ground speed that is a multiple of 60 makes the math simple. It’s NOT a precise calculation because a nautical mile is not 6000 feet, but it’s close enough. And at low level KCAS is essentially ground speed.

420 KGS = 7NM/min
480 KGS = 8NM/min
540 KGS = 9NM/min
600 KGS = 10NM/min

Flying Phantoms around Germany 35 years ago, the nominal max ground speed we were permitted to fly was 450 KGS (which you quickly realize is 7.5NM/min) with permission to fly .95 mach IP to target. I would push it up to 540 in Mil power on occasion, but typically stayed at 450 for the WSO’s sake. In the States and the Pacific, Phantoms would fly low level at 480 knots ground speed. Prior to ARN-101 we had a mediocre INS that could drift up to 3 NMs an hour and still be within tolerances.

[editorial remark] So back to the OP Malc’s situation. Based on the notion you’re flying at low altitude, 350 KCAS (or 360 based on my experience) is IMO terribly…painfully…excruciatingly…I have a death wish slow for an F-16. The point I’m making at Malc’s expense (nothing sinister mate) is that I’ve seen YouTube videos of guys tooling around at low level and making pop-up attacks at 350 KCAS. That’s fine if you can get your A-10 to go that fast, but it sucks in the F-16. And to be fair, I had some Jabo Alpha Jet guys at Furstenfeldbruck tell me they flew at 360 KIAS.[/editorial remark]

If on the other hand you’re up around FL180, 350 KCAS should put you somewhere around 480 KTAS. But then you have a different navigation problem and you have to adjust for winds…the Jurassic multiple of 60 technique doesn’t work because your HUD indicated/calibrated airspeed is significantly different than your ground speed. Thankfully the jet is smart.

Allow me to share some insight regarding a 1 minute early time of arrival over a turn point. Generally the critical arrival time is your TOT (time on target) and not some turn point prior to the IP. Pulling the throttle back slightly or checking away works. One potential problem with trying to follow the speed carat to arrive “on time” is that the closer the airplane’s clock gets to the steerpoint planned arrival time, but you’re not at the steerpoint, (meaning you’re late) the greater correction the carat will command as it tells you to speed up to make that arrival time to the second (the carat will drive up the speed scale). On the other hand, if you’re even just a little early, the closer you get the carat will command a greater slow down to the point it’s worthless. The moral of this being the carat is less useful when either your airplane or the airplane’s clock is close to the steerpoint and its arrival time. So the remedy is to select a steerpoint further along your route.

[Stevie]

Just to point up your observation about the caret RhoBee, I’ve figured out over time that there is a point at which to stop watching the caret and watch the TOT vs the clock on the DED. Depending on your speed, this can be someplace inside of 10 miles to the steer point/target…at least, that’s what I’ve noodled. Adjusting throttle to match actual times on the clock I can consistently arrive within a couple seconds of TOT. At least, I can in BMS.

[RhoBee]

@Stevie:

Just to point up your observation about the caret RhoBee, I’ve figured out over time that there is a point at which to stop watching the caret and watch the TOT vs the clock on the DED. Depending on your speed, this can be someplace inside of 10 miles to the steer point/target…at least, that’s what I’ve noodled. Adjusting throttle to match actual times on the clock I can consistently arrive within a couple seconds of TOT. At least, I can in BMS.

I agree completely. That’s exactly what we were taught…you taught yourself. Good on ya. The carat can give you a “warm fuzzy” (for non-Americans that’s just a sense of well being) in regard to your timing as long as you learn to accept being a little early or late.

[rmax]

My 2 cents. I now have the increment steerpoint mapped to my Warthog. Whilst I am flying I quite often increment to see what speed I need to do make TOT, and adjust accordingly (or miss out STP if it is not going to make me a tactical worse solution).

Reading Rhobee’s post, does make me wish we had a proper F-4 model + avionics in the SIM. There is something about the double ugly that still makes my heart flutter when I see it.

[Rybo]

@rmax:

There is something about the double ugly that still makes my heart flutter when I see it.

I’ve seen a single airborne F-4 in my life, and indeed was glorious to behold. I think it’s one of the most beautiful fighters of all time, certainly the most beautiful of it’s era. There’s really nothing like seeing a big, smoky, 60,000lbs fighter barreling towards you at 400 knots and 300AGL and then seeing those two GE J79’s light up as it blows past.

Here’s my all time Phavorite Phantom Phootage:

Sorry for the hijack…a worthy one IMO. Back to TOT talk

[Mikaa]

Is there any official documentation that helps with the planning aspect of what you’re discussing RhoBee? Or even Dee-Jay’s example of offset rule of thumbs. I apologize in advance if the answer lies in the RTFM realm, I just haven’t had time to sift through the vast array of manuals and official docs that are included with BMS. I’m really interested in the climb scheduling, descent planning, and low level nav planning aspects. i.e. purposely building flight plans to allow for TOT adjustments old school style. Staring at the DED is fun, and incredibly useful, but what if it fails and/or you don’t have the magic computer… GS checks, the lot, lay it on me!

[Redshift20]

@Mikaa:

Is there any official documentation that helps with the planning aspect of what you’re discussing RhoBee? Or even Dee-Jay’s example of offset rule of thumbs. I apologize in advance if the answer lies in the RTFM realm, I just haven’t had time to sift through the vast array of manuals and official docs that are included with BMS. I’m really interested in the climb scheduling, descent planning, and low level nav planning aspects. i.e. purposely building flight plans to allow for TOT adjustments old school style. Staring at the DED is fun, and incredibly useful, but what if it fails and/or you don’t have the magic computer… GS checks, the lot, lay it on me!

Rhobee’s post is the bogey dope on the subject. The biggest thing is not flying a direct route to the target, you need to plan some additional legs that will help you manage your TOT. If you simply fly direct to the target, then at any point if you are late, you will never be able to make it up. You need to create a flight plan that is non-linear, meaning with some extra legs along the route. By creating a flight plan that isn’t direct if at any point you are late, like Rhobee was alluding to, you simply select a steerpoint that’s down the route and just like magic you’ll be back on time for your attack. TOT is +/- 30 seconds so you actually have a lot of wiggle room, provided you planned a solid route to control the timing.

Other methods of control are flying a DME arc around a steerpoint (good when you’re early), holding (also good when you’re early), ect. But truly the simplest method is controlling the timing by flying a route that is not direct to the target and going to direct to steerpoints if you’re late or if you’re on time, flying it as planned on speed all the way to the target.

[Dee-Jay]

Other methods of control are flying a DME arc around a steerpoint (good when you’re early), holding (also good when you’re early), ect. But truly the simplest method is controlling the timing by flying a route that is not direct to the target and going to direct to steerpoints if you’re late or if you’re on time, flying it as planned on speed all the way to the target.

Do not know that for time management in combat area. IMO, this is a heavy workload for “nothing” while you need your brain resources for something else. A 90° offset (or the 60° offset : triangle method) from your next route is way easier.

[Rybo]

I can think of a lot of things that are a heavy workload, but flying an arc isn’t one of them for me personally.

[RhoBee]

@rmax:

My 2 cents. I now have the increment steerpoint mapped to my Warthog. Whilst I am flying I quite often increment to see what speed I need to do make TOT, and adjust accordingly (or miss out STP if it is not going to make me a tactical worse solution).

An excellent technique.

[Redshift20]

@Dee-Jay:

Do not know that for time management in combat area. IMO, this is a heavy workload for “nothing” while you need your brain resources for something else. A 90° offset (or the 60° offset : triangle method) from your next route is way easier.

Well I am certainly not challenging your method as that is clearly a good way to control timing as well, in fact I think I liked your post. Specifically section 5.5.5.4 of the BEM relates to this subject and these are a couple of several ways to skin the cat:

5.5.5.4 Route Timing. The objective is to hit the target on time. Starting the route on time, at the planned airspeed and heading, will help work towards achieving this objective. As a technique, allow some delay time between the planned takeoff and the start-route time. This extra time should compensate for late takeoffs, delays en route, or unforecast winds. Although flying faster than programmed, or cutting off part of the route can be used to make up time, fuel or threats may not allow it. Depending on the situation, it may be better to adjust TOT/TOS rather than burn excessive fuel to make up time. Be aware of the maximum route adjustment for the mission, both for time and fuel considerations.

5.5.5.4.1 Early Arrival. If you takeoff as planned, or early, delay arriving at the start-route point. Use the TOT/TOS to help pick a speed. If, after slowing to the minimum practical speed for your configuration and threat level, TOS function still displays early arrival, some techniques are:

5.5.5.4.1.1 Start the route early and fly the first few legs slower than planned until on time. Maintain tactically sound airspeed.

5.5.5.4.1.2 Arc around the start point until you compute it, then it is time to turn towards it. Figure the time to fly direct from present DME to the point, add 15 seconds for a 60-degree bank turn of greater than 90 degrees and turn to the start point that much before planned jump-off time. (See Figure 5.5, Arc to Start Point.)

5.5.5.4.1.3 Hold in a Racetrack pattern, either en route or at the start-route point. ATC restrictions may require that you fly the pattern in the route structure, so know
where you should and should not hold.

5.5.5.4.1.3.1 Method One: A viable variation of the TOT/TOS clock technique is to start the turn inbound, using a steep angle of bank (approximately 60 degrees), when the clock shows a 30-second early arrival. In order for this method to work, holding airspeed must equal route airspeed, and you must plan to be 180 degrees from the inbound course when 30 seconds early occurs. This method works well when holding in a threat area.

5.5.5.4.1.3.2 Method Two: Use GS required on the TOS page. Turn in and accelerate with 3 to 4 Gs when the required GS is 50 knots below desired route speed. This method also requires you to plan to start 180 degrees from the inbound course, and is best used when holding more than 15 NM from the selected steerpoint. The primary advantage to this method is that holding is accomplished at lower power settings (saves fuel).

So I’m of the opinion that you should have more than one method to achieve a desired result, especially when flying a jet, you can never have one too many techniques can you? Finally you should choose the best method for the given tactical situation and one or another may be a better option based on your needs for a given flight. I’ll definitely be adding your 60* method to my bag of tricks, I do appreciate anything I can learn and hope you found this just as useful for you!

[RhoBee]

@Mikaa:

Is there any official documentation that helps with the planning aspect of what you’re discussing RhoBee? Or even Dee-Jay’s example of offset rule of thumbs. I apologize in advance if the answer lies in the RTFM realm, I just haven’t had time to sift through the vast array of manuals and official docs that are included with BMS. I’m really interested in the climb scheduling, descent planning, and low level nav planning aspects. i.e. purposely building flight plans to allow for TOT adjustments old school style. Staring at the DED is fun, and incredibly useful, but what if it fails and/or you don’t have the magic computer… GS checks, the lot, lay it on me!

I have a collection of articles from 30+ years ago, about low level navigation and various techniques. I’ll start another thread when I get them scanned. Just a heads up, I’m scanning photocopies, I suspect they will be hard to read since the print is a bit faded. I’ll mess around with the contrast, hope for the best.

For some quick and dirty Rules of Thumb…I’ll scan some squadron stuff that might help, realize the drag index and fuel flow numbers will be off since I was an A model guy. Just to clarify, it wasn’t so much that the route was planned to allow for TOT adjustments, guys that had flown F-4s would often work backwards from the target. What I mean is first plot the target on a map, and then using a template (think plastic ruler measuring time and distance at a specific ground speed or I kid you not, a piece of string approximating 10 minutes flying at 480 knots ground speed) work backwards to a decent IP, back to decent turn points, back to the FLOT/FEBA and then back along the min risk transit route, all the way back over your base (or tanker track). With this exercise that takes all of 60 seconds you now have a really good idea of your no sh*t time required to meet your TOT and your fuel required based on your Drag Index. From that you build in time, a cushion by planning to get airborne, or leave the tanker track to enter the outbound min risk route with a little time to spare.

I attached three PDFs. The USAF Combat Plotter was a standard issue item. In the RF-4 I used it to draw my map (Triangle = Target, Square = IP, Circle = Turn Points and the Curves = turning ground track based upon the planned ground speed). When I got to the F-16 we didn’t bother with drawing the arc of your turn but simply connected a straight line from circle to circle. There’s an elegant simplicity not worrying about turn radii. The 420 GS Template is a Luftwaffe product. They also had 360, 480, and 540 templates, I picked this one up at Bremgarten’s Base Ops. This is what I was describing earlier. And the Fuel Flow gouge for the F-16A.

Along the right edge of the 420 GS template is the Time scale. You may note to the left of the Time scale is the Fuel Flow scale. And if you look carefully to the left at the 6:30 mark you’ll see 1.04. What you can’t see is the whole template and to the left at the 13 minute mark is 2.08. This is the fuel flow for a German RF-4E with two wing tanks at 420 KGS. So if I were planning a mission at 420 KGS, and I wanted to quickly estimate the mission time, I’d have my thumbs at Zero and 10 minutes along the template and work backwards from the target counting in 10 minute increments…10, 20, 30. Then I’d put my thumbs at Zero and 13 minutes (because that’s where 2.08 is), again work backwards from the target to get an approximate fuel required to get to the target after adding a standard STTO (start, taxi, takeoff) fuel burn…counting 2 thousand, 4 thousand, 6 thousand. Again this is what I would do as an RF-4 guy.

In the F-16 I would still take a piece of string or scrap of paper (from the map I was cutting up) and mark Zero and 80 NMs. Why 80? Remember 480 divided by 60 equals 8 NM per minute? So my string/paper scrap is measuring 10 minutes flight time. Then do that rough measurement starting at the target, working backwards to get my time enroute. Now I’d multiply that time in minutes by Fuel Flow PPM number, say 132 ppm for 480 KGS at sea level. Or…you knew there had to be an or didn’t you? Or to calculate your own gouge, as an example, one thousand pounds divided by 132 pound per minute equals 7.5757 (minutes). Multiply 7.6 minutes times 8 NM per minute means you will burn a thousand pounds of gas for every 60 NM you fly at 480 KGS at sea level. Up at 10K’ your fuel flow is an even 100 ppm, (easy peazy fly 10 minutes burn a thousand pounds) so every 80 NM at 480 KGS at 10K’ you’ll burn a thousand pounds. Plus add 1200 to 1500 pounds (taken from the bottom of the page and rounded up) for STTO to sea level or 10K’ because I’m not coming out of AB until 300 KCAS.

I can appreciate that I’ve presented a lot of math in public, but the take away is this. My technique was to roughly measure flying time in 10 minute increments, and estimate fuel burn in one thousand pound increments. That’s what I was trying to show.

That’s more that you asked for, but it’s a start. I’ll dig up some more stuff.

[RhoBee]

@Dee-Jay:

Do not know that for time management in combat area. IMO, this is a heavy workload for “nothing” while you need your brain resources for something else. A 90° offset (or the 60° offset : triangle method) from your next route is way easier.

Dee-Jay I agree with you about enroute. The example Redshift posted is a technique that was carried over from 30 years ago and it was specifically developed in Tactical Air Command in the USA to meet very strict low level entry times. That was the only time we ever talked about it (USA Visual Routes). Generally we just took a TLAR (“that looks about right”) guess or flew a racetrack holding pattern aligned with the entry. The DME arc was not a typical technique in the Jurassic era.

Enroute, your solution is elegant.

[Tomcat84]

key to success: push on time If you plan your route and know your assumptions speed wise etc and go for an on time push then you should not be surprised by suddenly being a whole minute early with only 15 miles to go.

How to push on time? Build in a 5-10 minute holding just ahead of your push point and compute your required push time that will put you on time for your route.

Once in your holding, how do you nail your push time? One recommendation is using one of the methods posted by Redshift of turning inbound when showing 30 seconds early (during your turn the ETA will bump up and end up around on time).
The higher altitude you are flying / the heavier your config is (GBU-31s etc), the more you may need to bump the 30 seconds up to 45-60. If your holding speed is lower than your push speed then you may also want to start accelerating once you start getting close to push time so that the calculations start using the correct speed OR pushing the turn in time a bit closer to 20-30 seconds prior and then accelerating as you go hot to get on speed and on time.

Of course, your holding may be confined to a certain area so you cannot just keep flowing cold for 50 miles until your time to go hits 30/45 seconds early, but if you just keep flying your 15 mile or whatever legs without thinking ahead you could find yourself on your hot leg but being a minute or 45 seconds or whatever early. If you turn outbound at that point you will eat up all your time and become late, and if you keep going hot you will push early. If you do find yourself in this position you could do an in place 90 turn in one direction (if airspace allows it) to eat some time and then in place 90 back hot. But to prevent it my technique would be that once the actual time hits 3 minutes before push, and you are on the hot leg, but early, turn outbound. This (should work with a heavy config) will give you 30 seconds to a minute each to use for your turn cold and your later turn back hot and one to two minutes to eat up while flowing cold/hot in between (about half the time will be spent flowing cold and the other half will be hot when you are inbound to the push point for your actual push).

Make sense?

And then if you really have a specific TOT to hit but you don’t know how much time it’ll cost you to deal with any threat you encounter then you can decide to either push early (but then you may be early if this threat does not materialize) or you can as already mentioned I believe) plan a route that is not the shortest possible so that you can still cut off certain parts if you need to make up time that you lost dealing with threats. If the threat doesn’t show up you fly the full route and use time that way.

But to answer the original question, if I was early with 15 miles to go I would probably just do an in place 90 right, kill some time, then in place 90 left. (or left - right of course ) or a 360 or something if I was just single ship.

[Frederf]

Climb scheduling can be gotten out of the -1 supplement which will list things like time, fuel, distance based on certain schedules (MIL or MAXAB). For a strictly-timed sortie I doubt a “just in time” takeoff for a straight flight plan would be used. Instead there is a planned hold one steer prior to a gateway “push” steer which you hit on time straight through and then keep that schedule through the rest of the flight.

E.g.
Steer 1, takeoff
Steer 2, hold
Steer 3, push
Steer 4, whatever

Take off and fly some nominal climb schedule to 2. At 2, depending on the time, fly holding patterns until the speed to reach 3 matches your planned ground speed through 3. Depart 2 toward 3 doing minor adjustments to cross 3 both on time and on speed. From then on it should be pretty easy to stay on schedule. I know it seems like it’s one extra step to separate the hold and the push gate but doing them in two places has a lot of benefits. It’s hard to depart a turning hold at the exact perfect time, speed, SA and formation aren’t the best. Especially where push point is also package join you don’t want to do that in the middle of a hold. If other parties are late and you have to rolex or scrub being one step earlier in the flight plan makes reacting better.

I would plan all descents as penetration descents which are 350 KCAS, boards out, idle and I think there’s a table for that in the book as well. That’s a tactical method of descending for recovery but I don’t know the kind you might use not associated with recovery. Is there a sort of tactical en route post hole for rapid altitude changes? What about slick descents in Indian country? I don’t know. I mean in the modern world if there’s a tactical necessity there’s a computer which can simulate it to high precision if you need custom performance data.

Low level nav is make a strip map and find visual landmarks and pencil in times next to them. If you’ve got the power to play with it’s possible to precalc a table of “add X knots for Y seconds late” to a part of your leg. You might build in an Option A/Option B leg split if you need to snip a large chunk of time.

I don’t know how much it helps but the USN Patpubs are freely available and a good resource. https://www.cnatra.navy.mil/pubs-pat-pubs.asp