Jimmie H. Butler
Information on Writing and the War in Southeast Asia

The "Prop Versus Jet" Controversy

 During my research for Crickets on a Steel Tiger, I came across documents that upset me by the obvious bias against highly effective propeller-driven aircraft.  Lt. Gen Momyer, Commander, 7^th Air Force, was known for having a strong bias for jet aircraft and against prop-driven aircraft.  I’m guessing that is the source of some of the faulty information I came across.  Since Colonel Heinie Aderholt, 56^th Air Commando Wing Commander was the main proponent of the effectiveness of prop aircraft, based on his extensive frontline experience, his career suffered some because of his opposition. 

Those of us who directed a number of airstrikes against the Ho Chi Minh Trail know which aircraft were more effective in putting bombs on the target.  My comments at the end come from my combat experience in 1967.

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The "Prop Versus Jet" Controversy

The second season was one in which major efforts were made to improve the effectiveness of the aerial forces assigned to challenge the Steel Tiger.  It was quite natural that questions would arise about the relative effectiveness of the various aircraft, which could be committed to the interdiction campaign.  By mid-1967, a major controversy was brewing over what mix of propeller-driven and jet-powered strike aircraft would be the most effective in the Vietnam  War.  In the author's opinion, the two key issues were (1) an aircraft's effectiveness in destroying targets, and (2) an aircraft's capability to operate, with an acceptable level of aircraft and aircrew losses, against the Communist antiaircraft defenses.  As the controversy deepened, it appears that some considerably less objective criteria were used to help justify conclusions about the proper force mix.

The first item, which seems open to question, is the November 1966 message reporting the combat evaluation of the A-26 in Laos.  It listed conclusions that totally underestimated the prop-driven aircraft's potential.  Such a mistake could be attributed to the effects of the rainy season on the combat evaluation conditions.  By November, the A-26 crews had certainly not had the opportunity to demonstrate their capabilities against the enemy's full-scale operations.  However, the invalid claim that "the present mission in Laos would be more effectively accomplished by F 4 aircraft" ^[i] fits into the pattern of questionable claims that certain jet aircraft were far superior to certain propeller-driven aircraft in overall mission accomplishment.

            The main controversy centered on recommendations to deploy squadrons of A-1 Skyraiders in place of some F-100 and F-4 squadrons.  These recommendations were strongly opposed in a June 26th, 1967 message from Seventh Air Force to CINCPACAF.

1.  Strongly oppose suggestion that two A-1 squadrons replace two F-4 squadrons in South Vietnam or that two or three F-100 squadrons be replaced by A-1 squadrons.

2.  The A-1 is a limited capability close air support aircraft that can only be used under closely controlled circumstances.  Whenever enemy firepower is strong, these aircraft have had to be replaced by jets.  We are presently using the F-100F in Route Package I as FAC aircraft because enemy defenses have increased to the point where survival of the A-1 in this hostile environment is doubtful.  The air commander cannot meet the demands of the war in SEA unless he is able to deploy full strike potential against the enemy where needed and when needed.   These demands may range from a massed effort against vital targets within the heavily defended Hanoi area to concentrated interdiction in the panhandle area of Laos and North Vietnam, rapid and responsive close air support of friendly forces in heavy contact with the enemy or to the air defense of friendly bases.   The A-1 simply cannot meet this requirement; therefore, the air commander becomes limited in his capability to deal with the enemy under the terms of  the situation at hand.  To heed the various demands, we believe the fundamental principle of the high performance tactical fighter is the proper solution.   The F-4, F-105, and F-100 have demonstrated the validity of this concept.  On the other hand, the A-1 has vividly evidenced, the limited, utility of a specialized aircraft.  To replace F-4s and F 100s with A-1s would represent a regression in tactical flexibility.  This is inconsistent with current and long-range planning since our requirements have been directed toward a more sophisticated strike force incorporating a night/all weather strike capability.

3.  If the USAF is forced to accept an obsolete Navy aircraft in order to meet the FY/68 force requirements, they must be additive as an interim means to meet the immediate demand, but never as a replacement for the high-performance fighter.

4.  In summary, replacement of F-4s and F-100s with A-1s is completely unacceptable because we simply cannot accomplish the mission.  With the increasing demand for close air support because of more operations by ground units, there is a need to be able to use the fighter force across a wider range of requirements.  We cannot meet these operations missions with A-1s. ^[ii]

It can certainly be argued that mission planners were faced with a variety of challenges and needed a highly capable force, which possessed great flexibility.  However, the case against the A-1, and "the limited utility of specialized aircraft," appears to be grossly overstated.  Many of the frontline combat crewmen, who watched the Sandy pilots perform in their Skyraiders on air rescue missions, will undoubtedly find it hard to believe that such a characterization of the A-1 could have found its way into an official Air Force document.  The general criticism against specialized aircraft appears representative of the late 1960s attitudes.  DOD emphasis was on multipurpose aircraft not optimized to carry out a specific role.  While flexibility is an important tenet of basic Air Force doctrine, one needs to look back only a generation earlier to recall American P-47s, P-51s, B-17s, and B-29s, etc., performing extremely effectively in specialized air missions.

The controversy was further fueled by a September 29th, 1967 report prepared by systems analysts in the Office of the Secretary of Defense.  Entitled "Analysis of the Use of Propeller Aircraft Vs. Jet Aircraft in Laos," the report concluded, among other things, that "propeller aircraft are approximately 10 times as effective as jet aircraft, per sortie in destroying trucks and watercraft in Laos." ^[iii]  This study and the "analytic" efforts to refute that conclusion are discussed in more detail in the summary of the third dry season of Operation Cricket.

Most combat crewmen did not have access to the classified documents that were being generated; however, many of the NKP's fliers sensed that there was some unexplained bias against the operations conducted by the prop-driven force.  The restriction on most operations of propeller-driven aircraft over North Vietnam had seemed somewhat capricious.  The antiaircraft deployments along Routes 912 and 137 certainly did not justify the ill-defined border as a reasonable line of demarcation between jet and non-jet operations.  By the time the "Nail Fanny" operation had been through its days of delay waiting for jet weather minimums—most of the combat crewmembers at NKP were convinced that something more than just weather was behind the delay.  The Nails' and Air Commandos' attitudes involved a deep commitment to accomplishing the mission.  An aircraft's effectiveness rather than its type of powerplant should be the primary factor in comparing aircraft.  There was one thing sure about the controversy: it did not end with the second season.

In conjunction with the subject of capabilities of specific types of aircraft, it is important to address an interesting and noticeable difference in the accuracy of some of the jets.  The Navy A-4 Skyhawks, diverted often into the Steel Tiger, were the most impressive group of jets that the Nails controlled in the spring of 1967.  The A-4 was designed primarily for the attack role and carried a good bomb load for such a relatively small aircraft.  The A-4's better overall accuracy was based on more than just the capabilities of the bombing platform.  Variations in the rules governing the employment of the Air Force and Nave aircraft influenced the accuracy of the bombs delivered.

As stated earlier, Air Force jets were limited to a minimum altitude of 4,500 feet above the ground when bombing in Steel Tiger.  As a result, bomb release points were significantly higher above and farther away from the targets than were the release points of the low flying Skyhawks.  In addition, the Air Force concluded that repeated passes against defended targets were the most dangerous for the aircraft and aircrews.  The basic Air Force policy, therefore, was to release all bombs on a single pass.  While additional passes are more dangerous, they are also more accurate.  Multiple passes give the pilot the opportunity to learn wind conditions, aircraft idiosyncrasies, etc., on the first pass.  The last bomb should be the best bomb dropped.  In summary, while both Air Force restrictions had the laudable goal of reducing aircraft and aircrew losses, the restrictions also reduced the effectiveness of the unguided general-purpose bombs used in that phase of the war.

The rules governing the length of combat tours were the other main policy difference that influenced the airstrikes in Steel Tiger.  The Air Force out-country pilot's tour length was based on surviving 100 combat missions over North Vietnam, with missions in the Route Package VI area around Hanoi being the most deadly.  The Navy pilot's tour length, however, lasted until his aircraft carrier finished its assignment in the Gulf of Tonkin.

These rules meant that neither pilot received any credit for missions over Laos.  Ironically, the Navy pilots, whose tour lengths were not affected by working in North Vietnamese airspace had to fly over North Vietnam to reach Laos.  Air Force pilots, who needed to penetrate North Vietnamese airspace to log one of their 100 "counters," normally flew directly into Laos from Thailand or from bases in the northern part of South Vietnam.  As a result, the system encouraged Air Force pilots to divert to North Vietnam or rush through airstrikes in Laos to save enough fuel for a quick "route recce" across the border into North Vietnam.  The hurried efforts turned the Laotian mission into a counter, but tended to degrade both the accuracy and the effectiveness of the Laotian strikes.

The FACs readily recognized that the Navy pilots' motivation was entirely different.  They were obviously eager to work with the Nails.  The Navy pilots had no need to finish quickly  and could not take their bombs back onto the aircraft carrier.  If enough fuel and time were available, the Navy pilots dropped one bomb at a time, using the FAC targets like a practice bombing range..  They appeared to work hard at improving their skills so they would be better prepared for the next day's mission, which might take them back among the heavy defenses around Hanoi.  It was not uncommon for the FAC's comments to be augmented by those of the flight leader if a wingman got sloppy or failed to follow instructions.  Most FACs concluded that the overall accuracy of the A-4 was a direct reflection of the intensified effort of its pilot.

The problem with the tour length policy also became apparent to the SLTF (Steel Tiger Task Force).  SLTF Status Report No. 20 on August 20th, 1967, reported the seriousness of the problem.  The SLTF Commander called for efforts to curtail the unjustified diversion of strike flights from Laos into RPI (Route Package I).  He also pointed out that "in the long term, the only solution is to equalize the counter program between Laos and NVN.  Either stop counters in RPI and Tally Ho or add Laos as a counter mission." ^[iv]

            This example illustrates that weapon systems should not be judged and categorized in simplistic terms.  Their effectiveness depends not only upon the aircraft's inherent capabilities but also on many other things, including policies governing employment of the weapon systems.  

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This section came from the last main chapter of Crickets on a Steel Tiger, which covered action against the Ho Chi Minh Trail from November 1967 through October 1968.

Aircraft Controversy Intensifies

The OSD Study

By late 1967, the controversy intensified over the effectiveness of prop-driven aircraft compared to aircraft powered by jets.  Near the end of the second season, systems analysts in the Office of the Secretary of Defense (OSD), conducted an analysis that set the stage for the expanded debate during the third season. 

The OSD analysts reached three basic conclusions. 

            1.  Propeller aircraft are approximately 10 times as effective as jet aircraft per sortie in destroying trucks and watercraft in Laos.

            2.  The loss rates per sortie for propeller aircraft operating in Laos were 4 times greater than the loss rates for jet aircraft.

            3.  If the North Vietnam significantly increases the AAA defenses in Laos, the loss rate for propeller aircraft will increase more rapidly than for jet aircraft. ^[v]

The OSD study was based upon statistics for January through August 1967.  During that period, propeller aircraft flew 25 percent of the attack sorties and accounted for 75 percent of the moving vehicles destroyed or damaged.  Most of those sorties were night missions flown by the Nimrods and Zorros of the 56th Air Commando Wing at Nakhon Phanom.

With such statistics clearly stressing the effectiveness of propeller aircraft, analysts projected the potential results of increasing the numbers of propeller aircraft targeted against the Ho Chi Minh Trail.  Since additional A-26s and T-28s were not available in significant numbers, the analysts projected replacing a jet squadron with 18 A-1s.  The new Skyraiders would fly strike missions in Laos, and other jet sorties would be diverted into North Vietnam to make up for the one less squadron of jets available for attacks against North Vietnam.  Although that scenario decreased the number of air attacks against Laos, the Skyraiders were expected to damage or destroy an additional 504 moving vehicles per year. ^[vi](146A)

By mid-December 1967, the analysts updated the study with data for September 1967.  The statistics still favored the propeller aircraft, although the advantage of vehicles destroyed per sortie decreased to a ratio of nine to one from the previous ten to one.  The analysts also concluded that it cost thirteen times as much to destroy or damage a truck using a jet aircraft than using a propeller aircraft.^[vii]??

The Seventh Air Force View

At about the same time, the Seventh Air Force Directorate of Combat Analysis produced a working paper entitled “Comparative Analysis of Propeller vs Jet Aircraft.”  Although an informal position dated December 18, 1967, the working paper appeared to represent the Seventh Air Force position on the September 1967 study by OSD. 

The analysis by Seventh Air Force took a broader perspective, looking at air operations in Laos and Route Package I for the first 10 months of 1967.  This study included the following points that suggest a different perspective on the relative effectiveness of jets and propeller aircraft. 

a.  An analysis of year-round effectiveness must consider the antiaircraft defenses in Route Package I and the influences of the monsoons.

b.  The data included built-in biases that favored propeller aircraft.  For example, a lower percentage of jet sorties attacked trucks.  Therefore, a lower number of truck kills per overall sortie could be expected.

c.  Jets often carried ordnance for flak suppression or attacks against industrial targets in North Vietnam.  When these aircraft diverted to strike targets in Laos, the jets could not be expected to be as effective as the propeller aircraft, whose armed-reconnaissance loads were optimized for attacking fleeting targets.

d.  Since air defenses would continue to restrict propeller aircraft from North Vietnam, A-1s would be much less effective during the summer when few trucks normally were in Steel Tiger.

e.  Even though operating almost exclusively in Laos, propeller aircraft had a loss rate almost five times higher than the  

f.  Propeller aircraft were only twice as capable as the jets in destroying or damaging trucks where air defenses were permissive and when jets did not carry loads optimized for killing trucks.

g.  Only about one-twelfth of the total strike sorties attacked trucks, so that rate should be increased significantly “...  before additional forces could be justified for this mission.”

h.  If additional forces were to be committed to the truck-killing mission, F-4s would be more effective than A-1s. When all “appropriate” factors were considered, an F-4 squadron would destroy 162 to 300 more trucks per year than a similarly targeted squadron of A-1s. ^[viii]

The Memorandum from the Secretary of Defense

Referring to the December version of the OSD study, a memorandum from the Secretary of Defense asked the Joint Chiefs of Staff to comment on the advisability of replacing two F-4 squadrons in Thailand with two squadrons of A-1s.  The memo estimated that the A-1s would destroy an additional 1,200 trucks per year.  Since Seventh Air Force would need fewer F-4 sorties in Laos, the same number of jet aircraft sorties could be fragged into North Vietnam even with two less F-4 squadrons.  The old A-1s were less expensive to operate and maintain than the F-4s, so the study projected cost savings of $23,000,000 over a two-year period.  The improved capability to destroy trucks would not be without costs, however.  The study estimated that substituting two A-1 squadrons would result in the loss in combat of 16 additional aircraft and eight more pilots than would be lost with the original mix of aircraft. ^[ix]

CINCPAC Staff Response

In response to the questions about the effectiveness of propeller aircraft and jets, the CINCPAC staff analyzed “...all combat air operations in the Laotian Panhandle for the month of December 1967”. ^[x]  The CINCPAC study concluded “...there is little evidence to support the conclusion that propeller-driven aircraft are, in fact, superior to jet aircraft in their capability to destroy or damage moving vehicles.” ^[xi]

The central part of the analysis, appearing in Table 8, took into account all attacks against motor vehicles except those whose results were reported as “unknown.”  The study found that:

It can be observed that, categorically, jet aircraft are considerably more effective, both by day and by night, in the conversion of a sighting to a truck casualty, and in the number of truck casualties produced per aircraft attack. ^[xii]

The CINCPAC analysts provided a listing of several of the “significant inherent differences between jet and prop aircraft which can affect mission performance.” ^[xiii]  These are summarized in the overall discussion of the two studies, which found the jets to be such effective truck killers.

Table 8: COMPARISON, BY AIRCRAFT TYPE, OF TRUCKS DAMAGED/DESTROYED IN THE LAOTIAN PANHANDLE, DECEMBER 1967 ^[xiv]