Sorry, as this is going to be a bit OT from just the RNZAF, but I wanted to better illustrate just who is operating what. The ex-RNLN P-3C Orions now in service with Germany and Portugal (as P-3C CUP+) were ordered in 1978, and flying by ~1981/1982, initial examples had RNLN undergoing flight training in Florida in Sept. 1981 and ferried to the Netherlands in 1982. The 13 P-3C's were then sold by the Netherlands in 2006, with the five Portuguese Orions getting upgraded to the P-3C CUP+ standard in 2011. The eight German P-3C Orions started phase one of their upgrades in 2014, with contracts being signed for phase two towards the end of 2017. The updates to the mission systems should permit the aircraft to continue providing valuable service, but the aircraft are getting a bit long in the tooth being nearly four decades old. The upgrades and aircraft refreshes may permit continued operations until the 2030-2035 timeframe, but I have to question how well such MPA, even upgraded, would perform when compared with new designs like the P-8 or P-1. From what I have been able to gather, an estimated USD$400 mil. was allocated to upgrade the German P-3 mission systems, re-wing them, etc. While that is not an insignificant amount, I doubt such a refresh would deliver a sensors and avionics package comparable to new, integrated designs. Germany also operates a pair of Dornier Do 228 LM to monitor marine areas with radar, E/O and other sensors for pollution control among other tasks. France operates (18-22 out of 28 built, I believe) Atlantique 2 MPA which were designed in the early 1980's with deliveries starting ~1989. At the time of introduction, the smaller Atlantique 2 could carry ~one-third the stores of the larger P-3C Orion built at the same time and had a MTOW of ~18,000 kg less. Again, upgrade work was started ~2013 to keep the ATL2 in service until ~2032 but the aircraft themselves are ~30 years old at this point. It also might be telling that in the early 1990's, when Germany was considering replacing it's Atlantic MPA from the 1960's, Germany opted to upgrade the Atlantic's for another decade of service and then replace them with 2nd hand Orions, rather than spend money on new build Atlantique 2 MPA. As a side note, it looks part of the Atlantique 2 upgrade done by Thales was derived from work Thales did for Turkey on the MELTEM II programme to deliver MPS-configured versions of the CN-235MP. Italy has replaced it's Atlantics with the four P-72A which is a version of the ATR 72MP kitted out with radar and E/O systems, but is not equipped for ASW as it lacks sonobuoys or an acoustic processor. It is worth noting that this replacement happened very recently, from 2016-2017. The Italian Coast Guard also operates versions of the ATR 42MP. The Hellenic Air Force has a handful of P-3B Orions, though their condition and capability is something I question given the age and economic crisis Greece had, AFAIK work is underway to return four to service. I am attempting to confirm if the Hellenic Coast Guard still operates Reims-buit Cessna Caravan II aircraft in a maritime patrol configuration. The UK we already now got out of MPA ops when it retired the Nimrod, but has ordered the P-8A Poseidon so will be getting back into it. Norway currently flies the P-3C Orion but will be replacing them with P-8A Poseidons. Spain operates some P-3 Orions upgraded in 2007 by Airbus, but also operates the C-212, and CN-235 in maritime patrol/surveillance configurations. Belgium's MUMM operates a Britten Norman Islander for North Sea surveillance. While the RNLN has sold it's P-3 Orions, the Coastguard still operates a pair of Dornier Do 228-212 aircraft for maritime surveillance/SAR. The Swedish Coast Guard operates a trio of Q300's in a maritime surveillance configuration. Finland operates a pair of Dornier Do 228 via the Border Guard to provide maritime patrol and pollution spotting/control. Looking through the above list, there are quite a few aircraft that I would consider 2nd tier maritime patrol or surveillance aircraft. Of the Atlantique 2's and P-3 Orions on the list, most of them have either received or are in the process of being MLU/SLEP'd to get up to another 15-20 years of service out of them, at least from the time of contract signing. Where this gets squiffy though is how comprehensive some of these upgrades are in terms of the mission systems, as opposed to rebuilding or re-winging the aircraft. To further illustrate this, as part of Thales upgrade of the Atlantique 2, a compact, new AESA version of the Searchmaster radar based off the Rafale RBE2 AESA radar was fitted. This new Searchmaster AESA weighs 75 kg and can be fitted to medium-altitude long-endurance (MALE) UAV's, as well as medium helicopters and fixed-wing prop or jet aircraft, much like the slightly heavier Telephonics APS-143 radar in use aboard some US helicopters and the HC-144 Ocean Sentry. For those who continue to operate the P-3 or France, those MPA are likely going to come up for replacement some time in the 2030 timeframe, and if basically all the operators got together to develop a comparable replacement, the total fleet size is most likely going to be smaller than Japan's P-1 fleet size. That includes replacing of the RNZAF and RCAF Orions. That and the time it would likely take to have a consortium develop such a replacement means that it would need to start soon, if not already have commenced.