The Boeing 737 - A living dinosaur of sorts, loved by airline bean counters.

The Boeing 737, with over 11,000 units delivered, is one of the most successful commercial aircraft of all time, with a production run exceeded only by the 1930s DC-3/C-47 (over 30,000 built, but mostly for wartime needs) and by the 1940s Antonov 2 which had a production run of over 18,000. It is the most mass produced commercial jet, just ahead of the Airbus 320 series, which delivered over 10,000 aircraft.

The Boeing 737 was designed in the early to mid sixties and began commercial revenue flights in early 1968. Throughout its long production run, the B737 was the subject of 3 major upgrades. The 737-100 and -200 were the first generation of the type, the difference between the two being essentially the length of the fuselage, with appropriate power and weight modifications. They are called the Original Generation.

The second generation, that came in the early eighties, saw the installation of new, more fuel efficient CFM-56 high bypass engines, installed to compete with the new MD-80, an upgrade of the DC-9 series, and with the brand new Airbus 320. Those second generation 737s were the Boeing 737-300, -400 and -500, called the the Classics. The main difference between the 3 models of that generation were again, their length, weight and power.

The third generation, called the New Generation (NG) was released in the late 90s, and featured a redesigned wing with a wider wingspan and larger area, greater fuel capacity, longer range and higher weights. It was equipped with the new CFM-56 high pressure ratio engines, and and a glass cockpit with FMS, and upgraded interior configurations. These were the were Boeing 737-600, the -700, the -800 and the -900. As before, the main differences between the 4 models of that generation were length, power and weight. I have no idea how Boeing was able to use the original 1967 type certificate considering the new wing, the new fuel tanks and the new engines but they did it. The B737NGs sold like hotcakes. This was the most successful 737 yet.

The fourth and last generation, which did its first commercial flight in 2017, is the Boeing 737 MAX. They are the Max -7, -8, -9 and -10. These featured the installation of the very fuel efficient CFM Leap-1B engine. As in other models, the major difference between the -7, -8, -9 and -10 series are length, power and weight. The 737 MAX were created as a rapid response to the A320Neo series introduced by Airbus, a re-engined and very fuel efficient version of earlier A320 aircraft. Boeing secured over 5000 orders for the Max series aircraft.

For all these B737 models, from the 1968 B737-100 to the yet to be certified Boeing 737-10, Boeing used the same type certificate and tried to maintain the illusion that they all required the same type rating for pilot certification. In the United states, there is only one type rating for all Boeing 737 models, although most countries, including Canada, decided to break up the type ratings in three groups (B73A, B73B and B73C), with only the Third and fourth Generation (NG and Max) grouped into one Type rating. On my FAA licence, it says "B737". On my Canadian licence, it says "B73C" (NG and Max).

In Nov 2018 and then again in March 2019, as Boeing was gearing up to build the most B737s in its history, disaster struck. Two 737 Max crashed within 5 months of each other, which led to the grounding of all MAX versions of the type. It was discovered that the MAX fiasco was brought about by the numerous engineering changes that Boeing had to make to hang a large diameter CFM Leap-1B engine onto an airframe originally designed to accommodate a small diameter Pratt and Whitney JT8D. One of those modifications was the now infamous Maneuvering Characteristics Augmentation System (MCAS), a new system that did not exist on previous B737 models, but that Boeing, in its quest to maintain type commonality (not only for certification purposes but also for pilot certification purposes) between all its B737 models, decided to present, not as a new system, but as a modification of an existing aircraft system. As such, Boeing decided to keep MCAS out of its Flight and Training Manuals, so the FAA would not require NG pilots to have to receive extra training to fly the MAX. The investigation's conclusions into how the MCAS was downplayed by Boeing, and how it was overlooked by and accepted by the FAA, soured the cozy relationship that had, until then, existed between the Boeing certification staff and the FAA aircraft certification staff.

And this brings me to the subject of this post. The current tug of war between Boeing and the FAA about the 737's lack of any modern crew alerting system, as is now required for certification for all modern jets. What many people do not know, is that the Boeing 737 Max, with all its large flat screens that make the aircraft appear as any other modern airliner, is devoid of any Crew Alerting System such as the EICAS or ECAM that can be found on all other modern aircraft, and that have been a certification requirement on these aircraft for many years. Boeing, by claiming that the B737 Max was still a sub-type of the original type certificate of the 1967 B737-100 model, had managed to dodge that requirement through FAA exemptions.

The technical issue is explained in detail in this article. The B767 and B757 that were designed by Boeing in the late 70s and which first flew commercially in 1982 and 1983 respectively, were certified with Crew Alerting Systems. The Boeing 747-400 and -8, the B777 and the B787 all have it. From Airbus, the late 70s era A300-600s, and A-310s, as well as the later A320s, A330s, A340s, A350s all have such a system. Embraer Regional Jets have it. The Bombardier Regional Jets aircraft have it. The Russian Sukhoi 100 SuperJet has one. Even the Chinese COMAC C919 has one. The B737s do not and many people are now pushing back against the FAA granting Boeing yet another extension for a waiver to this requirement for the certification of the MAX -7 and MAX -10, the two B737 Max models that have not yet been certified by the FAA.

What is a Crew Alerting System ?

In older jets, there were bells, lights and gauges that provided the flight crew with information on the status of every system on the aircraft : engines of course (engine power, oil pressure, oil temperature, oil quantity etc), but also all the other aircraft systems like the fuel system, the pressurisation, the hydraulic system, the flight controls, the brakes, the air conditioning, etc. All aircraft systems were directly connected to the cockpit and could simultaneously and independently send a fault or fail warning the the flight deck, in the form of a bell, a warning light, or a gauge indication. Until 1967, aircraft above 80,000 pounds were required by certification regulations to have a flight engineer to manage those systems. That year, the FAA lifted the 80,000 pound limit for aircraft that would be designed in such a manner to not overload the pilots, like no longer needing fuel management such as switching fuel tanks in flight. The B737-100 was one of the first aircraft to be certified under those new rules. A few large aircraft certified after 1967 still had flight engineers because of their complexity (B-747-100, DC-10 and L-1011) but within a few years, all aircraft were designed and certified with a two man crew, the flight engineer being replaced by a Crew Alerting System.

A modern Crew Alerting System is a sort of computer that all aircraft systems report to. Instead of having each aircraft system reporting its fault or fail status to the cockpit through bell, a gauge or a light, all systems report to a computer which displays the status of the system to the pilots through one or two computer screens. The computer will not only display any failure in text and in graphic form, but it will indicate for earlier versions which paper checklists need to be carried out (B757 and B767) or in more modern aircraft (A320), will contain the checklist itself. In these more modern versions of Crew Alerting Systems, the checklist have a feedback capability, meaning, for example, that when a pilot is told to open a cross-feed valve, the system knows when the pilot has opened the valve and the line indicating in the ECAM instructing the pilot to open the valve will disappear once the pilots does so. At the same time that the pilot is told to open that valve, the button for the valve in question, is lit in amber, to help the pilot locate it. More urgent items such as engine failures or fires will light in RED. Should the pilot activate the wrong button, the system will catch the error. The crew alerting system also prioritises the failures and the crew actions. For example should multiple failures occur simultaneously on an aircraft not fitted with a modern crew alerting system, like an engine severe damage which would simultaneously cause an engine failure, the loss of hydraulic and electric power, a hydraulic leak and rapid cabin depressurization, in a B737 or in an older aircraft with a flight engineer, all audio, light and gauge announcements will activate in real time and the crew will need analyse the fault to decide on what needs to be done first. With a modern Crew Alerting System, the computer will show the most urgent action to be taken on the top line, followed by the next and so forth until all actions are taken in the right priority order. They are also categorized by urgency with colors such as red, orange, blue and green. The switches are all dark (unlit), except those that need to be activated and so forth.

Although the Airbus A320 series aircraft (A318, A319, A320 and A321), the main competitors to the B737, were designed with ECAM (the Airbus Crew Alerting System), Boeing, to maintain the original B737 type certificate and to allow current B737 pilots to fly the new generation B737 aircraft without having to undertake new type training, resisted installing any modern Crew Alerting System on any version of the B737 and this is what is now a matter of contention between Boeing and the FAA. The FAA had given Boeing a waiver to certain Regulations of part 25 that allowed the Boeing 737 Max -8 and -9 to be certified without a Crew Alerting system but that was before the two Max accidents that grounded the Max fleet for several years. The waiver was based on the aircraft's history of past accidents, but the two Max accidents were now added to a few more where the accidents were partly attributed to a lack of flight crew awareness, something that a Crew Alerting System would likely have prevented. The two MCAS related crashes featured multiple, simultaneous and conflicting warning messages (master caution aural and lights, PFD messages, overhead panel lights, stick shaker) that distracted, overloaded and misled the pilots. There are two planned models of the Max Generation of the B737 that have yet to be certified by the FAA: the shortest version of the series, the Max -7 and the longest ever for any B737 ever built, the Max -10. The waiver that Boeing had obtained to allow the B737 Max -8 and -9 aircraft to be certified without a Crew Alerting system expires on Dec 31 2022, and it looks as though Boeing will not meet that deadline before the Max -7 and Max -10 are certified. Beyond Dec 31 2022, any airliner produced in the US will be required by the FAA to be fitted with a Crew Alerting System.

(Although the Max Series of the Boeing 737 have large modern looking screens in their panel, these are mostly for show. They are not connected to any EICAS system. The electro-mechanical engine gauges of the B737-100 were replaced with digital gauges on the screens but that is about it. A Max pilot, when faced with a failure, must use his master caution panel, the aural bells, scan his screens, gauges, lights and dials scattered all over the flight deck to try to determine what is wrong with his aircraft. The overhead panel of the B737 Max is nearly identical to the one that the 1967 B-737-100 had)

Boeing now expects politicians in the US intervene and pass some form of legislation to force the FAA to extend the Dec 31 2022 deadline so that Boeing may, sometime in 2023, yet again certify a newly manufactured passenger airliner according to 1967 Airworthiness Standards. Even the Russians and the Chinese are not attempting to do such a thing.

All this so that they do not have to design a new aircraft capable of competing with the Airbus A320 Neo series aircraft. I think the B737 was a great aircraft for its time. But its time has now passed. It began commercial revenue flights 54 years ago.

Time for Boeing to get back to the drawing board and create the aircraft of tomorrow.