Spotting Jets with Binos or Scope (1 Viewer)

[HoosierGuy]

One of the things my brother and I have enjoyed doing is looking at jets in the sky as they pass over, high up in the sky. We always want more power. We've taken the eight inch telescope and tried to view and track them but the field of view is so small you constantly have to keep tracking the jets. We can see color schemes on the jets like red stripes down the middle or whatever. Sometimes we can make out big letters (sort of blurry) like FED EX.

What I want to know is - do any of you do this? Is there any type of binocular that can bring the jets up real close with a decent field of view? I don't want to zoom right in on the windows, I just want something powerful enough to make out how many engines and see the name on the jet tail wing.

What kind of power would you recommend? Would one of those stabilized binos be good?

Kind of crazy I know, asking about binos for "jetting" and not "birding." lol. Still, it's fun to do.

 

[Geoff Brown]

Why not try a scanner instead. It's a lot more interesting listening to the pilots flying overhead.

 

[sammyboy]

I have to admit I do this as well as watch birds! I did it a lot when younger with a pair of cheap Miranda 16x50s for hours in the garden, and still enjoy watching them go over from the garden now.

I would suggest that a 10x bin would be about the right compromise, those 16x were perhaps a bit too unsteady for watching high-flying aircraft (though I think the hours of trying to watch planes through them gave me very steady hands!).

 

[Kevin Purcell]

Well they are just big aluminum birds.

Canon IS bins might be a good option for that.

I generally don't have a problem with engine count or even rough ID for a 35,000 feet airliner but I doubt you'll find much to give you a nice view of the tail but can also track easily.

You have the standard magnification versus FOV trade off.

 

[FrankD]

We do this while up on the hawkwatch each fall....especially when hawkwatching is slow. Specific bird-related terms of the various planes, gliders and copters are often used.

I typically use my Pentax ED 65 with a wide angle 20x eyepiece to compliment my binoculars. This particular combination of size, weight and field of view make finding and tracking planes very easy.

 

[Steve C]

More than once I have looked up at a high flying aircraft. At 8x and 10x I can't see much difference, except the 10x is a bit bigger. Forget trying to tell if if is Fed EX or anything else. If you have some aircraft knowledge you can sometimes get the type of aircraft, but not much else. I have come to the conclusion that high enough magnification to provide some rest and easy movement to follow the flight is necessary. I can't say what the minimum magnification for Jetliner ID @35,000' is.

 

[Kevin Purcell]

Caution: back of the envelope calculation ahead.

If the plane is directly overhead then you aren't going to see the fin to ID the airline. So lets say it's at 45 degrees (because that's easy and you would get some view of the fin.

That aircraft then aircraft at 30000ish feet (10,000m) that's about 6 miles high and 6 miles (10km) away along the ground. Or a slant range of around 8.5 miles (13.6 km) away.

The fin of a 747 is about 30 feet or 10m high.

So the fin at 13.6km subtends an angle of arctan(10/13600) = 7.3e-04 degrees = 2.6 seconds of arc.

So to make that appear a decent size (say 10 degrees in AFOV ... about the width of your fist at arms length) you need to magnify it about 13600 times.

Even to make the fin appear 1 degree in size ( a thumb thickness at arms length) you need 1360x.

So IDing the airline of a plane is not going to happen.

You can do the same for the wingspan viewed from underneath to get a feel for how much magnification you need to ID the aircraft.

And for the birders ... yes, you can do the same sort of calculations for birds too.

 

[etudiant]

Hoosier,
Try the Canon image stabilized binocs, they make a huge difference for observing anything that is flying, including jets.
Of course you won't see much if a plane is at cruise altitude, then you'd be lucky to spot a red tailfin if the light catches the plane right, but engine number is very doable, plus there are only a few civil types, all pretty distinctive, so ID is feasible.
Assuming an active airport within 20 or so miles, you will have plenty to see as the planes climb out or come in, amply detailed for carrier ID.

 

[Surveyor]

So the fin at 13.6km subtends an angle of arctan(10/13600) = 7.3e-04 degrees = 2.6 seconds of arc.

Hi Kevin, I think you forgot the arctan step, which would lead to about 150 arc seconds, about normal unaided visual acuity. I know, with good visibility and light, I can see/detect large, cruising aircraft (not ID) especially if pulling contrail to aid in location.

Have a good day.
Ron

 

[Surveyor]

What I want to know is - do any of you do this? Is there any type of binocular that can bring the jets up real close with a decent field of view? I don't want to zoom right in on the windows, I just want something powerful enough to make out how many engines and see the name on the jet tail wing.

HoosierGuy,

Using Kevin P's caution, back of the envelope and middle of the night calculations and a lot of assumptions, the math might look like this:

If we assume acuity to match a Snellin Chart of 5 arc minutes for 20/20 acuity and perfect seeing and lighting I think we could assume the required power= distance in miles / 0.13 / object size in feet.

Example: A 747 engine opening is 84" or 7 feet. At a slope range of 8 miles the power required would be approximately 8/.13/7=9x. To see 2 foot high letters would be 8/.13/2=31x.

All this is unchecked and heat and humidity will affect this greatly, it may need a fudge factor of 2, or more, and of course needs to be field checked, but may be a place to start.

Have a good day.
Ron

 

[ronh]

Kevin,
It's funny you'd mention FedEx. That is the easiest of all jet insignia to read. I looked up at a distant FedEx jet with my 8x42 Leica (not that I'd recommend it for this particular specialty, it's just what I wear) and wondered, what were the odds that there was a fine binocular on that airplane, headed for the doorstep of some happy idiot? I didn't have an envelope with me at the time, unfortunately.

Anyhow, to get serious, one might rightly suspect that the world's champion plane spotters would be the Civil Air Patrol. This organization was founded in the hysteria following the Japanese's exquisite tactical success, and unfortunate strategic blunder, at Pearl Harbor. And yes, friends, it still exists. (I knew an otherwise intelligent, in fact extremely bright and cultured, gentleman who was allegedly a cadet. He did have a bad case of wandering eye. But I never broached such a personal subject with him.) I mean, you'd think that must be the place to go with your question. And it may be. But I am quite certain, however much airplanes interest you, you cannot possibly be ready for this: do you really wanna look at airplanes or what?.
Ron

 

[Kevin Purcell]

Hi Kevin, I think you forgot the arctan step, which would lead to about 150 arc seconds, about normal unaided visual acuity. I know, with good visibility and light, I can see/detect large, cruising aircraft (not ID) especially if pulling contrail to aid in location.

Have a good day.
Ron

Not sure which arctan step you think I'm missing ...

angular distance subtended by object = arctan of height of object over distance of object

Do you disagree? What did I miss?

The wingspan is about 7 time larger than the fin height (I was using the latter). And a 45 degree slant not straight up (which you usually don't look at the aircraft that way).

And I omitted the root(2) for seeing the fin at 45 degrees.

 

[Surveyor]

Not sure which arctan step you think I'm missing ...

angular distance subtended by object = arctan of height of object over distance of object

Do you disagree? What did I miss?

The wingspan is about 7 time larger than the fin height (I was using the latter). And a 45 degree slant not straight up (which you usually don't look at the aircraft that way).

And I omitted the root(2) for seeing the fin at 45 degrees.

tan=(10/13600)=7.35E-4
arc tan (tan-1) 7.35E-4=.042 degrees=150 arc seconds

On my way to doctor right now. I will check this further later today.

Ron

 

[sammyboy]

The science bit has mainly gone over my probably rather simple head!

However, when I've been watching high-flying aircraft going over, it has been possible to ID quite a few airlines and roughly what aircraft it is. However with the airlines there aren't a huge variety that overfly me, usually the easy-to-ID orange of EasyJet, BA's colours, or lower flying Ryanair/BMI aircraft from Birmingham airport which is about 20 miles away.

I'm not sure if the overflying aircraft here fly a bit lower than those in the US but I do find them relatively easy to ID with my 8x32 Minoxes or 10x32BN trinovids.

Back to what optics to recommend, this is perhaps sacriledge but perhaps a good quality pair of zoom binoculars and a monopod? Not those nasty '20-100x' zooms but a decent 8-16 or 8-25x version from a good manufacturer?

 

[Surveyor]

Not sure which arctan step you think I'm missing ...

Hi Kevin P,

I had looked at this several times before it dawned on me that 2.6 seconds was below the resolving power of most 42 mm bins. I know, from flying into various large airports, that I can see aircraft on the runways when within the airport traffic area (5 miles). Also IIRC, ARTCC would call aircraft 15 to 20 miles away when below positive control airspace and about 30 miles when under positive control and, if they were above the horizon and away from the sun, a lot of the time you could find them on first call.

I did make one other check this morning since I had never really looked for planes with binoculars. I stood around in the driveway this AM until I found a plane. I saw it with unaided eyes and then, with a 8x20 Ultravid, was able to ID it as a 747, I could easily see the hump and the 4 engines, vertical stabilizer, etc. I could not make out any windows, even in the cockpit area. The plane was WSW of me and traveling NW so I was looking at it right broadside so it may have been transient traffic out of Florida or departing Atlanta. Atlanta is the closest airport south of me that will support 747’s (11,000’ runways). V5 airway is very common traffic routing in this area (see sectional attached) and my closest point to V5 is about 17.1 (I live about 18.6 miles ENE of the Chattanooga VORTAC). I did watch the 747 and it made a transition turn about 20 degrees left, so I assume it was over the Chattanooga VORTAC at that time. Its altitude from me was about 20 degrees above the horizon but this is a guesstimate, not measured, which would probably put it around 35000 feet, the preferred altitude for 747’s.

Tonight I will calculate a compass heading to the Chattanooga VORTAC and take a lounge chair and a few beers out and watch for traffic and transitional turns to try to get a better handle on the distance. Using the algorithm above, a 231’ long plane would only need .6x to see and if the engine nacelle is about 20’ long, would only require 7.2x to see.

Best, have a good day.
Ron

 

[Kevin Purcell]

tan=(10/13600)=7.35E-4
arc tan (tan-1) 7.35E-4=.042 degrees=150 arc seconds

On my way to doctor right now. I will check this further later today.

Ron

Yes, you are right. I woke up and realized what I'd done. Right algorithm but hit the wrong buttons on the calculator

Using my previous numbers then I get 2.5 arc minutes (as you do: 150 arcsec). Which would mean the aircraft would be just visible as a dot to the naked eye.

So to magnify this to 1 degree (a decent fraction the field: enough to ID the aircraft from the tail fin) you need x23.7.

So perhaps teens or twenties magnification? So perhaps a Canon IS 15x50 or 18x50 would be a good choice to help find and track. Or a wide angle spotting scope on a tripod. I don't think bins are going to work so well but you might get away with 12x if you are steady (and if you have good eyesight).

For the aircraft itself the numbers would be rather larger.

Apologies for the mistakes above.

 

[HoosierGuy]

Ok, since I got my Zen Ed's 10's on Monday I've been waiting for jets to fly overhead so I can view them and find out how much detail I can see. All week there have been hardly any jets flying over.

Well,you all will not believe the "bird" I saw Friday evening. So the sun was going down and I went on a walk with one of my brothers near a cornfield/patch of woods. We've walked this area before. Anyway, He gets on his cell phone talking to our other brother.

I had my Zen Ed's 10's and heard a jet up in the air. I figured it was a passenger jet. I looked up and saw a strange thing in the air. I put the binos to my eyes and what did I see flying above? A B-2 Stealth Bomber! It was black and flat. It was definitely the B-2. I yelled at my brother "Look up there! Look up there!" and handed him the binos. He hogged them and watched the jet for twenty seconds or so until it disappeared over the horizon.

That's the biggest, and most expensive bird I've seen with my binoculars!

 

[Redeye171]

During the early 70' my MOS (job discription) was a Redeye Team Leader (hence the screen name). As you may or may not know the Redeye/Stinger is a shoulder fired surface to air guided missile used by infantry troops.

We were deployed 5 to 10 kilometers outside a Brigade or Battalion sized unit in 2 man teams giving the area low altitude air defense. Before the electronic "friend or foe" electronic units arrived we depended almost entirely on visual aircraft recognition to determine an aircrafts identity. Our Redeye gunners were trained to recognize all aircraft in the world inventory within 4 seconds of first sighting using only the silhouette of the aircraft in question. Of course this required a great deal of practice and training and at no time did we use markings or numbers of any kind as aids. Markings etc. were not reliable in the field because it took too long to make a determination based on markings only. As HoosierGuy found out you can identify aircraft type, make and series by using the silhouette quite accurately. I can not remember the type/kind of glass we used - it did not seem to be remarkable and we most likely would not have time to use them in most situations.

Just an fyi.................red

 

[Kevin Purcell]

And to add to Redeye's comment the "military grip" (or thumbs-up grip as we call the civilian version so as not to scare the delicate birders) is nicely described in the Field Manual for the Stinger team (FM 44-18-1). We even have a clip from the manual on another thread showing the grip.

I noticed that in most of the manual chapter talking about scanning for aircraft they're just doing naked eye scanning (in a systematic manner) then using the bins for ID when the target is found. A whole other sort of birding in a way but rather similar in some ways to real birding with Jizz ID (and 7x bins).

 

[ceasar]

Hi Kevin P,

I had looked at this several times before it dawned on me that 2.6 seconds was below the resolving power of most 42 mm bins. I know, from flying into various large airports, that I can see aircraft on the runways when within the airport traffic area (5 miles). Also IIRC, ARTCC would call aircraft 15 to 20 miles away when below positive control airspace and about 30 miles when under positive control and, if they were above the horizon and away from the sun, a lot of the time you could find them on first call.

I did make one other check this morning since I had never really looked for planes with binoculars. I stood around in the driveway this AM until I found a plane. I saw it with unaided eyes and then, with a 8x20 Ultravid, was able to ID it as a 747, I could easily see the hump and the 4 engines, vertical stabilizer, etc. I could not make out any windows, even in the cockpit area. The plane was WSW of me and traveling NW so I was looking at it right broadside so it may have been transient traffic out of Florida or departing Atlanta. Atlanta is the closest airport south of me that will support 747’s (11,000’ runways). V5 airway is very common traffic routing in this area (see sectional attached) and my closest point to V5 is about 17.1 (I live about 18.6 miles ENE of the Chattanooga VORTAC). I did watch the 747 and it made a transition turn about 20 degrees left, so I assume it was over the Chattanooga VORTAC at that time. Its altitude from me was about 20 degrees above the horizon but this is a guesstimate, not measured, which would probably put it around 35000 feet, the preferred altitude for 747’s.

Tonight I will calculate a compass heading to the Chattanooga VORTAC and take a lounge chair and a few beers out and watch for traffic and transitional turns to try to get a better handle on the distance. Using the algorithm above, a 231’ long plane would only need .6x to see and if the engine nacelle is about 20’ long, would only require 7.2x to see.

Best, have a good day.
Ron

Pardon me boy, is that that the Chatta.............

Whoops, sorry, this is about planes not trains!:eek!:

Bob