Carrier aircraft navigation: How did they do it?

During the Pacific war Japanese and Alied carrier aircraft had millions of square miles of empty ocean to fly over, usually spent looking for each other's fleets. I know they had the usual map and compass and that was usually about it for most aircraft especially those with one man crews...i want to know how did they navigate accurately back to their carriers in all that ocean? What if they got lost in overcast or at night and couldnt even see the stars to navigate by? Could the carrier help them find their way back?
Anybody have any idea of the numbers or percentage of carrier aircraft lost simply because they could not find their way back to their carrier?

 

Just plain old fashioned navigation. Depart on one azimuth and return on another taking into account wind speed and direction. Navigation is a huge part of pilot training. I am sure in extreme cases, or where enemy attack was not probable, radio navigation would have been an aid to pilots as well.

 

My father was a carrier pilot in WW II, serving from 1941 until 1946 in the Pacific. He flew SBD's in 1942, was a flight instructor in the States for most of 1943, and returned to the Pacific flying F6F's from 1944 to 1946.

Over-water navigation was always one of the most difficult challenges that Navy pilots faced. Combined with weather which might change rapidly, navigational errors probably killed as many naval pilots as did the enemy. When flying from carriers, pilots were briefed on what courses to fly both outbound and inbound, and were advised of a "Point Option", which was the location the carrier expected to be at the time the pilots returned from their mission.

Things sometimes happened to cause the carrier to alter it's plans and in that case it wouldn't be at "Point Option". In that case, the pilot had two options; conduct a search for the carrier with what fuel it had remaining, or hope to pick up the homing beacon each carrier operated.

All US carriers were equipped at the start of the war with a device called the YE-ZB. This was a UHF (line of sight) transmitter which transmitted a Morse code letter denoting 15 degrees of a circle. If the pilot picked up a Morse "M" for instance and homed on it, then started picking up another letter, he would know he was moving an a tangential course in relation to the carrier; he would then turn and home on the strongest signal. Since this was a UHF device it worked better at higher altitudes. It wasn't extremely reliable and some pilots were better at using it than others, so pilots had differing levels of confidence in it.

Planes with multiple crew members, like SBD's and TBM's had an advantage in that the pilot could concemtrate on flying while a crew member was delegated to attend to navigation. Fighter pilots, of course, were most likely to become a victim of faulty navigation because they were by themselves, and air combat with enemy fighters would often cause them to become disoriented as to their location. My father once said he felt that perhaps as many as a quarter of all losses of carrier aircraft were due to the pilot becoming lost, but this, I think, was just a guess. In some exceptional cases, like Mitscher's command at the Battle of Philippine Sea, carriers might display lights at night to help lost pilots. In fact, Mitscher's task Groups not only displayed lights, they directed search lights straight upward, fired star shells, and turned on all deck lights on all ships, escorts included. This confused at least some of the returning pilots, at least one of whom made a landing approach on a destroyer.

 

Two ways, the old way and the new way.

The old way: USN carrier pilots were generally pretty skilled at navigation. One took into account the mission parameters - - - go so far at such and so speed and on such and so bearing, do whatever you supposed to do, then go back on this or that bearing to find the ship. Each pilot had a plotting board for keeping track of where he was based on the mission parameters. Before taking off, with some notable historical exceptions, he would be given the location of "Point Option" - the location of where the ship expected to be at the end of the time allotted for the mission. So starting from a known point, time, bearing, and distance navigation to another point, do your business, and time, bearing, and distance to a pre-plotted point.

The new way, as DA noted, was utilization of the YE-ZB homing system, developed by Frank Akers, which all USN carriers had at the start of the war. Without going into the boring details, this system used a morse code transmission of a particular letter for a particular bearing, a different letter for each 15 degree sector. This was a UHF line-of-sight system, so the higher you were the better. If the letter you were receiving changed, then you knew you were moving tangentially to the transmission point. You simply found the strongest signal and followed it back to the ship. In the early days of the war it was a fairly new system and some pilots were more proficient with it than others and those less proficient tended to be less believing. For example on the 4 May 42 Yorktown strike on Tulagi, there were 4 F4Fs very hurriedly sent off to deal with some F1Ms that were bothering the SBD and TBD strike planes. After performing their mission, shooting down 3 of the F1Ms, and shooting up a destroyer they happened upon, they started to head back to the ship. The division leader signaled for an increase in altitude to pick up the YE-ZB signal, but his section leader did not see the signal (although the section leader's wingman did). So the division leader and his wingman pulled up through the cloud layer, picked up the signal, and, after milling about a bit waiting for the other two, proceeded back to the ship. The section leader left behind had a problem, his radio did not work. His wingman's did. Eventually they came up through the clouds and the wingman picked up the YE-ZB signal. He also made radio contact with the ship and started flying a box pattern so the ship could get a good radio fix so to tell him which letter he should be listening for. Well, as far as the section leader was concerned, his wingman was flying in all sorts of odd directions for no apparent reason and finally signaled him to knock it off and then led the way back to Guadalcanal where they bellied in on Cape Henslow - - - with the wingman keeping a running commentary with the ship the whole time. Result was two of the ship's 18 F4Fs were lost for no apparent reason. The two pilots were rescued the next day through some extraordinary efforts by the crew of USS Hammann. Apropos of nothing else, I have the original flight instructions for this mission carried by the division leader. It clearly indicates the ship's location relative to Tulagi and the Point Option for the return. The division leader was clear in his recounting that the instructions would have gotten him back to the ship, but the YE-ZB was easier.

Even worse happened at Midway when the VF-8 strike escort improperly used their YE-ZB and all 10 of them ended up ditched at various locations. Fortunately for some of them some rather diligent PBY crews managed to find and rescue 8 as I recall. This was a combination screw up in that the flight was not given a Point Option and their own unfamiliarity with the YE-ZB system sealed their fate. They actually saw the smoke of the US task group off to their north as they headed off into the expanse of the Pacific, but were so screwed up in their navigation that the leader presumed he was looking at the Japanese.

Rich

 

Thanks for the info on US carrier aircraft navigation guys. I learned a lot.
How about the Japanese? How did they do it?
I know that the Japanese pilots and aircrew all knew how basic navigation to get from point A to point B. But as it has been pointed out, pilots do get confused after an air combat and Japanese pilots, like all other pilots, have this problem, too. So what system do they have in place to help their pilots return to their carriers?

 

As far as I know, the Japanese carriers had no electronic homing beacons or other navigational aids, and Japanese carrier pilots, at least early in the war, relied solely on good old fashioned "dead reckoning" navigation. I believe Japanese carrier aircraft with multiple crew members often carried radios which could take crude bearings on radio transmissions and may have used these whenever possible as rough navigation markers. But of course, Japanese carriers, just like American carriers usually tried to avoid frequent radio transmissions. At the start of the war, Japanese aircrew were trained in celestial navigation and thus sometimes had the opportunity to use this method to fix their position, particularly in the longer-ranged planes.

Japanese carrier pilots, flying fighters, frequently didn't even have radios in their aircraft because of weight and reliability issues, and therefore had to rely on nothing but compass and dead reckoning for navigation. They suffered the same problems as their American counterparts because of this, except that their planes were longer-ranged and that exacerbated their problems.

After 1942, Japanese carrier pilots seldom had the opportunity to operate from carriers in combat situations, more often flying from island bases, and their navigational problems may have been eased somewhat. But this was probably offset by the fact that newer pilots had less training and experience in over-water navigation and their losses due to becoming lost must have been severe.

 

As Larry pointed out, Independence served as a night operations carrier, as did Saratoga, Enterprise, and Bon Homme Richard. And the other CVs, by late 1944 each had a night fighter division assigned to the regular air group VF squadron. In the mid 1943 to late 1944 period, there were detachments from night fighter squadrons (VF(N)) on most carriers. Night carriers had air groups dedcated to night ops, all trained through, initially, Project Affirm at Quonset Point NAS and later thru NACTULant and NACTUPac.

 

Thanks DA. I was thinking along the same lines. This just shows the risks naval aviators from both sides face every time they took off from their carriers' decks.
Your answer also also made me think of how Saburo Sakai survived and managed to return to his base after his near fatal flight over Guadalcanal. Sakai was a naval pilot but he never was assigned to a carrier.

 

Did the Japanese ever exloit this system by using it to find the American carriers?

Bob

 

To my knowledge, the Japanese seem to have been unaware of the American carrier homing system, at least during the early part of the war. If they ever did use the YE-ZB system to locate American carriers, it was a closely held secret and hasn't so far emerged as an historical fact. Based on the known circumstances of historical encounters between Japanese and American naval forces in the Pacific, I would conclude that there is no evidence that the Japanese ever were able to use the YE-ZB system to fix the location of American carriers. There is some evidence that the Japanese, on a few occasions later in the war, did become aware of the presence (althoungh not the exact location) of American carriers by detecting unspecified electronic emissions (radar or radio).

It should be noted that both sides often deduced the proximity of enemy carriers by sighting single-engine aircraft operating hundreds of miles from the nearest air base. This is not the same thing as fixing the location of an enemy carrier task force.

 

I've often thought about this very heroic effort of Mitscher.

It seems to me that, regardless of the circumstances, if a decision results in a victory, the decision, after the fact, was obviously the correct one. Thus, the results of Mitcher's decision to turn on all the lights was correct.

What about the merits of this decision before the results were known. Did Mitscher really make the right decision or did he just luck out?

Bob

 

Well, it's a debatable matter.

Mitscher was gambling that the Japanese would not be able to inflict significant damage on his ships, even if they found them. He knew that there were only two agencies that might be able to harm his forces; subs and air attack. Mitscher's fliers had just inflicted a severe defeat on the Japanese carriers, rendering their air groups practically defunct. Mitscher did not know the exact details but he knew that the Japanese carriers had been badly damaged and the bulk of their planes shot down, so it was reasonable for him to assume that air attacks were highly unlikely.

The other threat, subs, was also unlikely to be able to inflict unacceptable damage on Mitscher's ships. Mitscher knew that American ASW against Japanese subs had been very effective in the past several months, and that the last American CV sunk by a Japanese sub had been in 1942. So he probably felt that the risk of sub attack against his fast moving carriers was minimal. Mitscher could logically argue in that time and place that the odds of the Japanese being able to attack his forces were relatively low and that the benefits of recovering a significant number of his fliers who otherwise would have been lost, outweighed the risk of damage to his ships.

Whether or not one agrees with that assessment depends on the weight given to the various factors involved. My father happens to have been there, although he did not peronally benefit from the decision, and always agreed with Mitscher's reasoning.

 

It would be difficult for an adversary to use the YE-ZB system to locate the point of broadcast. The system was line of sight only so you had to be higher than the typical reconnaissance missions in search of enemy ships. Even if one did pick it up (requiring some pretty fancy scanning equipment to lock into that one descrete frequency) all one would hear would be a repetition of a single letter that change to another letter as you flew into the next broadcast sector. That would not tell you a thing about which way to go. Short answer, no, the Japanese did not back track on the YE-ZB to find US carriers.

On the other hand, the Japanese turned on all the lights to recover their errant strike on the the night of 7 May 1942, long before Mitscher was credited with doing so off the Marianas. There were a couple of other instances, on both sides, prior to that as well. In the US Naval Aviation circles in which I grew up, Arleigh Burke, Mitscher's chief of staff and Gus Widhlem, his ops officer was most often credited with making that happen. The thinking was that there were probably no Japanese submarines in the area anyway.

Rich

 

From a previous post, the old way is described, ".... go so far at such and so speed and on such and so bearing, do whatever you supposed to do, then go back on this or that bearing to find the ship. Each pilot had a plotting board for keeping track of where he was based on the mission parameters. Before taking off, with some notable historical exceptions, he would be given the location of "Point Option" - the location of where the ship expected to be at the end of the time allotted for the mission. So starting from a known point, time, bearing, and distance navigation to another point, do your business, and time, bearing, and distance to a pre-plotted point."

Okay fair enough. I still have a question on the details though....wind direction obviously bears greatly on the HEADING you maintain to achieve any given COURSE over the earth's surface. As a pilot myself, I know that even modern winds-aloft forecasts can be substantially incorrect. Once those poor guys pass over the horizon and are over a featureless ocean, the only indication of wind speed and direction would be waves, but that is down at the surface.....How would aircraft, at any altitude above even 3000ft, know what the actual winds were well enough for open-ocean navigation?

I've seen references to a method where scout aircraft would operate in tandem with one aircraft hugging the surface and performing the navigation using observable wind data as indicated by waves, while the 'looker' sits high and just follows the low guy's navigational lead. However, this was in a procedures manual (ca. 1944), and I've never heard anecdotal references to this procedure during historical narratives of missions.

Can anybody confirm or correct on this?

 

USF 74B (US Fleet Instructions)

PART II 2000. TACTICAL DOCTRINE GENERAL

2100. SCOUTING DOCTRINE

2110. GENERAL.
Scouting from carriers includes patrolling, searching and contact scouting missions. All carrier types can be used for scouting. However, where choice exists, the planes best equipped for a particular scouting mission should be used. Consistent with the prescribed conditions of radar silence in effect, radar equipped planes should normally be used for search missions because of their wider and more efficient coverage of the area to be searched, particularly under conditions of low visibility. For information regarding the methods of ordering search and scouting missions refer to General Signal Book, Aircraft Section, pages 10B to 114, inclusive.

2111. Definitions.

(a) Fixed point of origin is a geographical point determined either by geographical coordinates, a definitely fixed object, or by a time-designated position of a reference vessel which is unaffected by the subsequent movement of such a vessel.

(b) Moving point of origin is a point maintained relative to a moving reference vessel, or an imaginary point moving along defined courses at defined speeds. When referred to a moving origin the area or line moves with the origin, whether defined by true or relative bearing

(c) Geographical area is a fixed area defined by bearings and distances from a fixed point of origin.

(d) Relative area is a moving area defined by bearings and distances from a moving origin.

(e) Visibility is the distance at which the objectives of the scouting operation can be seen and recognized.

(f) Search entails one complete investigation of the defined area, such that all parts of the area have passed within visibility.

(g) Observation (Patrol) entails repeated investigation of the defined area during specified time.

(h) Distance to be searched is the distance to be covered by the airplane's track from the point of origin along the median of the sub-sector to the maximum chord of the sub-sector.

(i) Scouting speed is a designated true airspeed.

2112. IMPORTANCE OF SCOUTING.

Efficient conduct of a search, filing of contact reports and tracking are of the utmost importance. The outcome of a naval engagement may depend on the pilot who makes the initial contact.

2120. INFORMATION FURNISHED SCOUTS

Prior to manning planes for any mission, scouts should be furnished information and allowed ample time to work out their navigation. Furthermore, they should be given as much of the following information as is known or can be estimated:

(a) The tactical situation.

(b) Friendly forces that might be sighted.

(c) Probable strength and position of enemy forces.

(d) Instructions for action after contact.

(e) Number of search planes to be launched.

(f) Search and attack frequency, calls and authenticators.

(g) Sectors to be searched and whether relative or geographical.

(h) Distances to be searched.

(i) Visibility range to be used.

(j) Scouting speed to be used.

(k) Expected time of landing.

(l) IFF code number.

(m) YE code, call and frequency of all carriers.

(n) Approach doctrine and recognition procedure for the day.

(o) Probable course and speed of Point Oboe if contact is made.

(p) Action in event of adverse weather.

(q) Weather conditions in search area.

2130. INSTRUCTIONS FOR SCOUTS

2131. SCOUTING ALTITUDE.

For purposes of accurate navigation, search altitude should be between 500 and 1,000 feet, varied to obtain best horizontal visibility range. As no satisfactory drift sight is available, the visual estimation of surface wind remains the basis of carrier aircraft aerial navigation. When two planes are working together, visibility range can often be increased by the following plane flying 500 to 1,000 feet higher than the leader.

2132. BAD WEATHER INSTRUCTIONS.

In the absence of specific instructions, the search pilot upon encountering reduced visibility must make an estimate of the situation and decide for himself whether to continue or return to the carrier. This decision will depend upon the extent and severity of the storm area and to some degree upon the tactical situation. Normally search aircraft should fly around shower areas and through weak fronts, thereafter continuing planned search, correcting navigation for any wind shifts encountered. Extensive storm areas should not be entered unless it is required by specific instructions for the search. In general the search pilot should cover as much of his assigned sector as can profitably be searched and still permit return to the carrier on schedule. A report of any areas not searched should be made immediately upon landing.

- - - - - - - - - -

Wind drift was usually guestimated by watching wave tops. Searches conducted by carrier aircraft were generally not terribly high altitude affairs. Attack profiles could be, but searches generally, no. While true, the higher one goes the greater the distance to the horizon, for search purposes, the higher one goes the smaller the potential targets become, thus making them harder to see, especially amidst clouds and such.

Rich

 

Thanks for reply. Yep, that looks exactly like what I saw as a reference. Okay, scouting missions addressed.

So now, what about those Attack profiles Rich mentions, or Long range patrol profiles (e.g. PBYs, H6Ks, etc.)?

1) Dive bombers flew to/from targets usually around 12 kft - 15 kft, right? Same dilemma....how did THEY know winds on those higher altitude missions?
2) Easy to conceive that larger aircraft on long range patrol had navigators capable of celestial navigation.....I've never been there, but I can't believe stars are visible anywhere below 25kft during daylight. Were such long range patrols typically operated at low altitudes similar to scouts?

Thanks.

 

Patrol aircraft with a dedicated navigator could use drift meters, celestial navigation, etc. to determine position. Celestial navigation includes the use of the Sun as a reference.