What are the advantages and disadvantages of the P-8 Poseidon and Kawasaki P1 in the maritime patrol aircraft role? They were made for the same role, but they are different. The P-8 is something like converted from a civilian design while the P-1 is military-purpose built. What does that mean? What does the different number of engines mean for missions undertaken by these aircrafts?

P-8 Posiedon (left) and Kawasaki P-1 (right) P-8 Posiedon and Kawasaki P-1 (source)

  • $\begingroup$ One is japanese the other is US. That's enough of a difference for some. $\endgroup$ Commented Feb 19, 2016 at 20:54
  • $\begingroup$ And what is the advantage? To be american, or japanese? $\endgroup$ Commented Feb 19, 2016 at 21:02
  • $\begingroup$ @user3624251 I think what ratchet is saying is that the P-8 is used by the US, and the P1 is used by the Japanese. Are you just asking what the differences are? Because I don't think there is much of a choice about which one is used for a particular country... $\endgroup$
    – Ron Beyer
    Commented Feb 19, 2016 at 21:32
  • $\begingroup$ I am not asking on the difference. I am asking on advantage and disadvntage. One has two engines, one has four, one was built as a military plane, the other was built as a civilian plane. I do not know what these think make of an advantage and what not. That's why I am asking, because they were made for the same role, but they are different. $\endgroup$ Commented Feb 19, 2016 at 21:41
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    $\begingroup$ Four engines is more survivable with respect to birdstrike damage than 2, a serious concern for an aircraft that will spend a great deal of time at low altitude hunting submarines. The P-8 lacks a magnetic anomaly detector and may not have any reason to fly at low altitude. $\endgroup$ Commented Feb 19, 2016 at 23:52

1 Answer 1


Both the aircraft were designed as replacements for the Lockheed P3C Orion when the P7 was cancelled. While the USN decided to convert a civilian aicraft (as is the norm for most MPA), the Japanese decided to design theirs from scratch (the aircraft was supposed to share a number of items with Kawasaki C2, which given the wildly different mission requirements, didn't go very well). Almost all the differences between the two aircraft, which share a number of similarities resulted from this differing approaches to design.

  • The P8 was derived from 737, a commercial airliner, which means that it is optimized for high speed, high altitude flight. Previosly, the MPA were optimised for low altitude operations. The P8, on the other hand has (relatively) highly swept wings with raked wingtips, optimized for high altitude cruise. This means the development of modified operational procedures for this aircraft.


Image from ainonline.com

The P1, on te other hand, is purpose built to be a more or less a one-to-one replacement for the P3C, optimised for low altitude operation with strnthened structure. The wings are swept less and the wing area is relatively more compared to the P8.


Image from battlemachines.files

  • Operating the aircraft at high altitudes instead of lower ones also means that the operating principles are different. It is the main reason for the P8 not having the Magnetic Anamoly Detector (MAD), which was available in P3C (as well as P1, in the long boom in the tail). Last heard, UAVs are being developed with MADs to overcome this issue.

  • The P1 has larger windshields (which makes sense, as the crew would be able to scan better for ships at lower altitudes) and more hardpoints compared to the P8.

  • The P8 has only two engines compared to the four of P1, a significant difference. For aircraft operated in long stretches over areas without airfields, this could be a real issue. While so far no issues have been encountered in this regard, the loss of an engine in a P8 is basically a mission kill, which is not an issue with the P1.

  • The from-the-scratch development of the P1 alos has enabled the use of fly-by-light controls, which is a first for operational aircraft, allowing for lighter wiring and lesser interference.

  • One significant advantage of the P8 over P1 is that being based on one of the most successful and widely operated aircraft in history, spares and support will not be a big issue.

  • $\begingroup$ Is the lack of MAD a big issue for a MPA? If there will be no unmanned plane in the area, what does that mean? That the P-1 would be ble to detect a subamirne while the P-8 not? I also notest that the nose of the P-1 is much bigger. Does it have a stronger radar? $\endgroup$ Commented Feb 20, 2016 at 8:09
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    $\begingroup$ @user3624251 - The MAD is a very short range sensor. You need to be kinda lucky for a MAD hit. You have to fly directly overhead a target at low altitude to find him. Even then, some subs are made from non-magnetic steels (eg, German Type 212, Type 214) or titanium (Soviet Sierra, Alfa, and Papa class SSNs, portions of the Typhoon's 10 pressure hulls). Magnetic silencing and diving deep will also reduce/hide a sub's magnetic signature. Wrecks in shallow water will also show false-positives (but these are often known and mapped). Basically, MAD isn't crucial for hunting subs. $\endgroup$ Commented Jun 27, 2017 at 5:45

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