"Okay so why in the world do you need a car to chase the plane?" This would probably be in the top 3 questions asked by anyone around the U-2 (right behind "We're still flying the U-2?" and "Why do we have U-2s still when we have satellites?")
It is odd to see, but hopefully after this, you'll understand a little more about this vital part of U-2 operations.
To get started, I'm going to hand it over to Cheese and Brandon (with Mikko cameo) who give a pretty good intro to MotorTrend.
A Wingman on the Ground
Most of the public has at least a vague notion of what a wingman is. I mean, we've all seen Top Gun, right? At the heart of the concept is "mutual support". You have each other's back. The chase car pilot is that wingman on the ground.
For the U-2, the chase car pilot is actually known as the mobile officer, or just mobile. It's a noun and a verb to U-2 pilots. "Are you my mobile today?" "Yep, I'm going to mobile like no mobile has ever mobiled before."
To start, the mobile is going to show up with the pilot and do all the normal things pilots do before they fly. Check weather, check currencies, check NOTAMs (or maybe glance at a page with NOTAMs), confirm the sensor and mission, etc. They're going to do all that with the pilot just like they're going to fly the mission that day, because, that, is just what they may have to do.
Short side story: A pilot is going to fly a mission tomorrow. He decides to chow down on a second helping of greasy chicken fried steak at the base chow hall (it's free food) plus several ice cream twix bars (because he "worked out" that day and deserves it). The next morning he eats a big greasy piece of fatty steak (again, free!) for breakfast. He goes on to make a pilot judgment call while suiting up that his body just won't allow him to be confined to a space suit that day or any further than about 50 feet from a bathroom. Suddenly, the mobile is now getting into a space suit and will not get to play Halo in the break room that day.
This completely fictionalized account could describe any U-2 pilot. The mobile is often the backup pilot for the day and has to be ready to jump in the seat if "things" happen.
Now that we know everything for the flight, the mission pilot and mobile part ways, with the pilot heading over to put on his space suit, and the mobile heading out to the jet with all the mission materials (this also includes all the personal materials the pilot wants to bring, like magazines, books, possibly, ahem, camera stuff). The mobile will do an interior inspection of the cockpit and load all the mission information, as well as a complete walk-around of the jet and aircraft forms check, looking for any maintenance discrepancies. The plan is for the pilot to be able to come out to the jet after doing all of the suit-up routine and tests, and be able to basically just jump in the seat and go. It is a little more complicated, and there's really not much jumping in the space suit, but that's the idea.
Once the pilot is in the seat, the suit technicians get to work strapping them in. The mobile gets on a headset and talks to the pilot directly about anything that came up during the preflight inspections or current issues with weather. Once the mission pilot is ready, he gives a big thumbs up, the suit technician unplugs him from the portable cooling vent and into the aircraft cooling (which, btw, isn't working until the engine is started). As the pilot starts to heat up, the mobile goes to make one last check of the equipment and connections, then shakes hands, closes the canopy and rushes back to the chase car.
We're all set to start the jet now. Just put the key in and go, right? Well there has to also be a ground power cart supplying just the right levels of AC and DC power to the aircraft. Also there has to be an air cart that supplies a huge volume of air to the engine to begin it spooling up. Oh and and a team of 3-4 crew chiefs to operate the equipment and prepare the aircraft to leave the hanger.
The mobile is (probably) not sitting back during all this, listening to a podcast, and sipping on a giant cup of coffee. He's observing the whole startup, watching for anything that might be unsafe, and ready to read checklists or go help the crew chiefs and pilots in an emergency.
Once all the pre-taxi checks have been accomplished, the mobile does one last sweep around the ramp and makes sure there's nothing and no one that will be endangered by the aircraft taxiing. Then he gives the pilot a "Ground crew clear" on the radio and away he goes.
Now I know that some of you must be saying "Why does a pilot need this extra set of eyes watching his every move?"
It really comes down to 3 basic truths about the U-2:
- The pilot has 50+ feet of wing sticking out each side of the aircraft.
- The pilot is in a space suit and helmet that limits his vision of those massive wings, and...
- The Space Suit Makes You Stupid 1
Safety basically dictates the necessity for more eyes with an aircraft so unwieldy and the pilot at a cognitive and visual disadvantage.
1 The Space Suit makes you Stupid is based on a 14 year observational study of other U-2 pilots along with multiple personal insights gleaned to come to this conclusion
The aircraft is now safely lined up on the runway, the pins that keep the pogo wheels locked in are removed, the pilot's ejection seat safety pins are removed, and clearance to takeoff is received from the tower. The mobile will give a thumbs up and salute the mission pilot. The mobile will now watch to make sure the pogo wheels safely fall away and if one is sticking, they'll tell the pilot to raise their right or left wing to get it to unstick. If it remains stuck in the wing, now it's called a Hung Pogo, and the mobile will help the pilot run through the emergency actions for that.
(Note: For the video below, please click on the title to send yourself to Youtube to watch. That way you can control the camera in 360 degrees.)
Now the aircraft is safely airborne. Nothing much to do now except kick back and play some Halo (I'm dating myself, aren't I?)
Well, there was a little bit more to it than that (although I won't deny that I might have partaken in a few break room shootouts). As the mobile, you do have to maintain at least some connection to the mission going on. Through various technologies, you can keep an eye on what's going on. You also need to keep an eye on what's going on at your base.
Because you're a good mobile, you've kept up on the weather and have learned that a line of thunderstorms are moving into the area in about 4 hours, right around when the mission is due back. It would take 3 hours to recall the jet if you made the call now. Or you could request they conserve some gas and plan to come back after the thunderstorms should pass. (Or you're jaded because the weather forecast has been wrong for the last week and you shrug and get back to Halo).
Either way, you don't have to make those decisions in a vacuum, as there's other supervision that can be brought into it who each have their own experiences to add. And, of course, the pilot whose butt might be flying through a thunderstorm gets the ultimate say.
Around an hour from landing, the incoming pilot will radio in his expected time in and any maintenance codes. These codes are to give maintenance a heads up on what to expect. Because of the Lego type build of the U-2 which is fit with various sensors, there might 5 or more contractors who each have a different piece of hardware on the jet and they'll be waiting to hear how each performed as well. The mobile will let the pilot know the current weather and any other important stuff (and apologize for not letting him know about the line of thunderstorms the pilot will have to pick his way through now). Then it's time to grab the keys to the mobile and head out for...the recovery.
Why would I call this the recovery phase and not just the landing. It's because the mission isn't over until the jet is parked and shut down; and a whole lot of pieces have to come together to make that happen.
The mobile had already passed the maintenance info on and let the pogo crew know when the jet is expected down and when the mobile is going out. The pogo crew are maintainers who have the special duty of taking care of the pogos after takeoff and putting them back in the wings after landing. Depending on the location, they may follow the mobile out, or already be in place out on the airfield.
The mobile is going to try to be out in place, ready to do the run-in on the jet at least 15-20 minutes ahead of time, probably more. (Sometimes a new pilot will have told you they are an hour out from the field and show up on short final 35 minutes later.) You want to be able to watch what the weather is doing, other aircraft, and so on. Then you're waiting, and waiting, and waiting...
Now comes the fun part. You've got the jet now approaching. You check its configuration, you hear them get cleared to land, and now it's up to you to put yourself in a good position to make calls for the landing.
This is not that simple. Your goal is go from zero to matching the aircraft's ground speed and dropping in about 50-75 feet behind the aircraft. You get much further away and you can't make accurate calls. You get much closer and it starts getting a little dangerous. Added to that, you have to do this in whatever amount of pavement is available to you and in whatever conditions. Some place like Beale has tons of concrete to maneuver and accelerate. Other places, like Osan below, might give you enough room to turn the car around and point it at the runway. You need power and control. You use your training to accelerate and turn as you need to get the car in the right spot.
Not only do you have to drive the car just right to put it in the right spot, now you also have to say the right things over the radio to the pilot. Like we've pointed out before, the pilot has really poor visibility of the runway below due to the design of the aircraft and the restrictions of the space suit. As the wingman on the ground, the mobile's job is to help the pilot put the aircraft in a safe position to land and come to a stop. The mobile does this through visual cues between the aircraft and other references like the horizon. Ideally, the aircraft will land slightly tail-wheel first, on centerline, with no crab (nose pointing any direction other than down the runway) and no drift (sliding sideways across the runway). And the flying doesn't stop just because the jet touches the ground.
In a minute, we'll go through several landing scenarios pulled from a variety of past training videos (spoiler alert: they don't all go great). These videos are captured on all student sorties and used for debriefing after the flight. I'm not in all of these but I get the honor of sitting either in the aircraft or car on several of these. Before going through these, there's some terminology you'll hear you should be familiar with:
- "The T" refers to the runway threshold, or where the landing surface starts.
- The main gear is the front wheel and the tail-wheel is the back one
- All the numbers said are the number of feet between the bottom of the main gear and the runway. For instance "10 at the T" means "the main gear is 10 feet over the ground at the runway threshold
- "Right rudder" or "Left rudder" are a command to the pilot to apply more rudder in that direction to align the jet with the runway
- The magic number is 2. The pilot is trying to get to 2 feet and hold it there until the tail drops. "Tail's up at 2" is an advisory call that the jet still has energy and the pilot still needs to work to keep the jet from landing.
- "Hold it off" and "Let it down" are directive commands trying to keep the jet from bouncing or dropping in from too high
All of this is done over the course of a few seconds. In the case of students, sometimes the challenge for the mobile (who is also an instructor) is to prioritize what needs to be said first and work your corrections from there. For instance, a new student may cross the threshold with tons of crab but is also cruising down to plant the main gear into the runway. I want to first stop the jet from bouncing with a "hold it off", then work on fixing the crab. Sometimes, the best course of action is to just say "IP take the jet" (Instructor Pilot).
The entire run-in process boils down to an art, where each type of landing, the aircraft configuration, airfield conditions, the mission pilot, and individual style will dictate what the run-in looks like and how the calls are made. Cadence and tone, plus the ability to adapt in real time play an important part.
Here are just some of the standard visual cues and associated calls used in most every landing:
The 10 foot call is typically the first call made by the mobile. It's not particularly important that it's made exactly at 10 feet. This basically establishes the jet in the landing phase and signals to the pilot that it's time to start working the jet to 2 feet and fix those crab and drift issues if they're still there. The cadence of the calls after 10 feet indicate the rate of descent. A nice smooth 10...8...6...5...4... is ideal but a quick 10,8,4 will probably be followed by a "Hold it Off!"
When the main gear appears to be just below but touching the horizon, the jet is at 2 feet. If the main gear appears to be sitting right on top of the horizon, the jet is at 4 feet. Either one of these is a good point to "re-cage" your eyeball and catch up on you calls as the mobile. This is where higher precision is necessary and it's why it's important to be close to the aircraft.
The mobile and pilot will be busy from this point on, fine tuning the aircraft position until landing and then beyond. The jet should arrive at 2 feet with some safe flying airspeed which means the tail-wheel will be higher than the main gear, as in the picture above. When the pilot tries to hold the jet at 2 feet, they are actually having to continuously pull back on the yoke, demanding more out of the aircraft which is losing lift because of the slowing airspeed. If done correctly, the jet basically rocks back, and the main gear never leaves its safe spot of 2 feet. If the pilot pull too hard, the jet rises, if not hard enough, it sinks into the runway and bounces off the main gear.
Oh and while all of this is going on, the pilot is also working the rudder pedals to align the nose down the runway and work the wings to get over centerline and not drift (but also be basically level at the same time). Which brings us to...
So picture a bicycle going over a jump and landing it perfectly. Now imagine that bicycle turning sideways in mid air and trying to land with it not aligned in the direction it's traveling. Bad things right?
The U-2 is no different. Cross-winds or poor control inputs will cause this crabbing over the runway. Having the aircraft aligned with the runway and traveling straight down that runway is key to preventing it from going off the side and into the grass. The rudder is what makes the aircraft yaw (or rotate) to the swing the nose in the right direction. The rudder pedals also control the tail-wheel which controls this at slower speeds once on the ground.
For the mobile to make good rudder calls, they need to be pretty much right behind the aircraft, like in the picture above. You can expect more issues with crabbing with students and high cross-wind days, and need to plan the run-in accordingly. It also helps to have a mental model of different situations so you say the correct input when you have a fraction of a second to decide what to say. For instance, I look at which side the tail-wheel is on compared to the main gear and will say that rudder input. In the picture above, I would say "right rudder" because the tail is right of the main.
Real Life Run-Ins
Now that we understand a little about the run-in, let's look at some real life examples. Again, these all come from student sorties and have instructors in both the aircraft and in the mobile. These are basically raw training videos and should be watched with sound. (You can also get a sense for why Mythbusters said it's totally "Plausible" that the U-2 is the hardest plane to fly-check it out)
Crabs are Bad
We've already established why the jet crabbing is not for the best. Now take a look as students try to figure how to work the rudder (and how not to).
Rockin and Rollin
One of the aerodynamic consequences of having long thin wings and large ailerons that control roll is that there is a large amount of "adverse yaw" created. Basically if you roll left using the yoke, the jet will roll left but the nose will pull to the right. This means that each input to roll the jet must be met with an input to the rudders. Most pilots know this as coordinating the flight controls. This is what happens when you don't do that in the U-2.
Don't Force the Landing
We've established that the jet should land tail-wheel first. There is no shortcut to force a landing before the jet has lost its flying energy and slowed down. Sometimes this is easier said than done.
Hating on the Flap
This video comes courtesy of the first time I did an interview flight as an instructor, flying with a student who has no time in the jet. This was the student's second landing ever in the U-2. I used this as an example for new instructors at how quickly things can go from seemingly not too bad, to damaging the aircraft. This was the perfect storm of ingredients to slam a flap into the concrete. The plane drifted off the center of the runway, which is a crowned runway, or curved, with the peak in the center. The student tries to initiate a correction to get back to center-line, over does the correction, then I intervene with an opposite correction to the left, which at this speed ends up completely stalling the right wing, directly into the crowned runway. That all happens in the blink of an eye. The result is a bent flap and broken skid plate on the right side.
This video does not involve a student but shows a mission jet landing at night. Forgive the quality of the video, it was taken about 12 years ago on a Canon Powershot. Imagine how hard or impossible this would be if the car was not close to the jet.
So the jet has landed, managed to stay on the runway, and come to a complete stop. One of the wings will eventually flop to the ground. Once it is safe, the mobile will clear the pogo crew in to put the pogos back in. This is done through good old grade school physics as they turn the jet into the world's biggest see-saw. They prop the heavy side up by pulling down on the opposite side.
With pogos reinstalled, the jet taxis back in to parking spot where it shuts down, and the pilot gets to climb out of the cockpit (and possibly, location dependent, have a post-flight refreshment at the jet.
Well that pretty much wraps up a day in the life of a U-2 mobile (aka chase car driver). I hope you've learned something and can use these new found skills the next time you merge into traffic. Leave a comment below and be sure to check out the prints, downloads, and merchandise in the store. I'll leave you with some shots taken while sitting shotgun, as I try to teach a student how to mobile (Dear God, it can be scary). Thanks for reading!