Tactics
Topic: Navy Carrier Landing question
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Posted by eber on 10-10-2003 8:34 PM
I've been searching the net for a good link which describes navy carrier landings - specifically wondering about approach glidepath angles - is it a 3 degree glidepath?

When you're visual, what does the Fresnel Lens (a.k.a. the Meatball) dictate in terms of glide path angle?

Thank you.
Posted by KenV on 12-02-2004 2:48 PM
The meatball is almost always set to a 3 degree glideslope, but can be adjusted down to a little below 2.5 degrees.  Never heard that lower angle used operationally.

The meatball tells you where you are vertically on the glideslope so you know immediately if you are high or low on the glideslope.  Too low on the glideslope and you get a ramp strike, usually not survivable.  (The ramp is the rounddown at the aft end of the carrier flight deck)  Too high and you overshoot the landing area. Survivable, but it makes you look bad.  Navy pilots HATE to "look bad around the boat".

The glidslope is set up to bring the aircraft hook to strike the deck just before the 3 wire, causing the hook to engage the 3 wire, an ideal landing.  EVERY carrier landing is graded, and a "perfect" landing score is "OK 3-wire".  Sometimes the hook will hit before the 3-wire but then bounce over the 3 wire and not engage it.  If that happens, it's called a "bolter".  The pilot applies power, climbs, and re-enters the landing pattern (a "go around").   In a bolter, it's unlikely the hook will engage the 4 wire because the aircraft landing gear will rebound before then and the hook should miss it entirely.  Under rare circumstances a 3-wire bolter can result in a 4-wire engagement. This is called an inflight engagement and is BAD because it can result in the aircraft being pulled down to the deck, rather than it flying down to the deck and then engaging a wire and being pulled to a stop.  The hook is designed to sheer off before that happens, but you can never be certain inflight engagments are rare, but they do happen every so often.  But even if the hook does sheer off and you're in blue water ops (far from land with no "bingo" airfield), you're still seriously screwed with no way to get on deck and no place to land.

Centerline alignment is also done visually, but you do that with the centerline stripe painted on the deck.  Since the landing area is angled to the left, and the carrier is moving quickly through the water, from the pilot's perspective, the centerline appears to be constantly crabbing to the right. 

The pilot's scan pattern "in close" is usually:  meatball, centerline, meatball, centerline, meatball, indexer, meatball, centerline, meatball, meatball, meatball.  The indexer is unique to Navy aircraft.  It is a little colored light system inside the cockpit that tells the pilot when he is at optimum angle of attack (AOA) for the approach.  Because the approach is flown on the "backside" of the power curve, AOA determines airspeed, and throttle determines sink rate.  This is opposite to normal flight.  In normal flight the stick controls up and down and the throttle controls airspeed.  To go "up" you pull on the stick and point the nose up.  To go faster, you open up the trottle. 

Flying backside, the stick and throttle functions are interchanged.  The stick instead of controlling up and down now controls airspeed (pull the nose up and you don't go up, you slow down) and the throttle controls sink rate (increase throttle and you don't go faster, you go up.)

Incidentally, there are lights on the nose gear the same color as the indexer lights inside the cockpit.  The landing signal officer (LSO) talks the pilot all the way to the deck and he can see those lights on the nose landing gear.  That way he knows if you are on, under, or over airspeed, very important for a safe carrier landing.

Trivia:  Navy aircraft have a slightly higher failure rate of the right main landing gear relative to the left because the pilot is constanty correcting to the right and so the aircraft tend to hit right wing low.

Hope this answered your questions.  I'll be happy to answer any more if you got 'em.  I'll also gladly answer e-mails, so feel free to e-mail me.
Posted by paddles on 02-05-2006 2:23 PM

Where do you get your information ???
Do you make this stuff up as you go along ???
Have you been watching too much JAG ???

The standard glidepath on the ship is 3.5 degrees.  We sometimes increase the glidepath to 3.75 or 4.0 degrees in conditions of high wind so that the "perceived glidepath" remains relatively constant.  (The glidepath relative to the earth being shallower than the glidepath relative to the ship due to wind over the deck / ship's forward speed.)

If your hook skips the 3-wire and you catch the 4-wire, it is perfectly OK.  This is a "hook skip" and is fairly common.  (It was almost routine for the A-6 Intruder.)  IT IS NOT AN IN-FLIGHT ENGAGEMENT.  An in-flight engagement usually occurs when a pilot over-rotates the aircraft during a late waveoff and the hook engages the wire before the wheels touch the deck.  This basically results in a tug-of-war between the airplane and the ship and you can guess who wins.  The airplane usually comes crashing down on the flight deck (still holding the wire), and frequently will break one of the landing gear.

We do not fly on the "backside of the power curve," but closer to L/D max (if you know anything about aerodynamics).  We fly at a constant angle of attack so that the pitch attitude of the aircraft remains constant and the hook touches down where it is supposed to... WHICH IS EXACTLY HALFWAY BETWEEN THE 3 AND 4 WIRES  which are exactly 40 feet apart on a Nimitz class boat.  If you increase pitch, it lowers the hook (risking an inflight, hook slap or ramp strike).  If you reduce pitch, it raises the hook, increasing the chance of missing all 4 wires (a bolter).

Under normal daylight conditions, THE LSO WILL NOT SAY A SINGLE WORD TO THE PILOT.  (I'm an LSO)  We will instead give a flash of the cut lights on top of the meatball to let him know that he is cleared to land.  Beyond that, we don't say a word unless he approaches the margins of safety.  Also, we do not use the lights on the nose gear for angle of attack, but instead look directly at the pitch attitude of the airplane.  If his indexers are stuck or inoperative, we must be able to tell him his speed via radio.

Let's see... what else.  If you miss the three wire, it is not a bolter.  IF YOU MISS ALL FOUR WIRES, IT IS A BOLTER.

The hook is not designed to break before the wire... It's not designed to break at all.  (I have personally witnessed several in-flight engagements.) However, if you do have a damaged hook (hook slap of the round down or hook won't come down/stay down), YOU ARE NOT SCREWED.  We have something called a barricade (maybe you've heard of it).  If you are out of divert range, we rig the barricade which is like a net that catches the entire airplane and brings it to a stop (usually with little or no damage to the aircraft).

PLEASE DON'T POST ANYMORE ON THIS TOPIC UNTIL YOU DO AT LEAST A LITTLE RESEARCH.  I happen to be a Navy pilot and LSO with over 400 traps.

 
Posted by Hammer on 03-06-2006 11:38 PM
I agree with what "paddles" had to say and add that I also have completed 300+ carrier landings.

I'd add that the "crab" factor is negligible and likely inaccurate since the wind direction is typically aligned with the angle deck by the direction the ship is moving.

Hook bounce is controlled by hook snubbers which, for the most part, keep the hook on the deck.  There is no reason to expect that having a hook skip the #3 wire will cause it to also skip #4.

Hope this adds something to your information database.