VELOCITY NEVER EXCEED (VNE)

We helicopter pilots have something called VNE which dictates the MAX speed that I can fly my helicopter.

Commercial jetliners certified under modern transport category regulations (FAR Part 25) do not use a VNE (Velocity Never Exceed) speed limit, as VNE is a design limit reserved primarily for general aviation aircraft and helicopters.

Instead, jet transport aircraft like the Boeing 737 MAX 8 use VMO (Maximum Operating Limit Speed) for lower altitudes and MMO (Maximum Operating Mach Number) for higher altitudes.

MMO establishes a safe boundary to prevent the aircraft from running into severe compressibility problems, high-speed buffeting, loss of control, or structural damage. It is the highest permissible Mach number (the ratio of true airspeed to the local speed of sound) allowed during climb, cruise, or descent

For the Boeing 737 MAX 8, these operational maximum speeds are:

VMO (Maximum Operating Speed): 340 knots IAS (Indicated Airspeed)
MMO (Maximum Operating Mach Number): Mach 0.82 (roughly 82% the speed of sound at altitude)

Structural Margin (VDF / MDF): The ultimate dive speed limits tested by Boeing (VDF / MDF) are higher than VMO / MMO to provide a safety buffer against structural damage or flutter in the event of an inadvertent overspeed.

THE RECENT FLYDUBAI INCIDENT

During the co-pilot's attack and manual control inputs, the aircraft entered an extreme dive in Saudi airspace, dropping over 16,000 feet in roughly 30 seconds. At its steepest point, flight data recorded a peak rate of descent reaching ~544 feet per second (approx. 32,600 feet per minute).

During catastrophic dive events or control loss incidents, rates of descent exceeding 20,000 to 30,000+ fpm have been recorded on Boeing 737 platforms before impact or structural failure occurred.

As the aircraft plunged from 34,000 feet down to 15,000 feet, telemetry indicates that the 737 MAX 8 rapidly exceeded its VMO limit (340 knots IAS), reaching estimated true airspeeds/groundspeeds approaching 500 to 550 knots before passengers and off-duty crew intervened to pull out of the dive.

Operational Limits & Structural Damage (VMO / MMO vs. VDF / MDF)

VMO/MMO (Operating Limit): 340 KIAS / Mach 0.82

VDF / MDF (Demonstrated Flight Diving Limit): Around Mach 0.89 to 400+ KIAS (the highest speed demonstrated during factory flight testing for structural safety). This is what the Boeing test pilots did during flight testing and certification.

(From the above data, it should be clear that the aircraft is actually built much stronger than what the Pilot's operating manual mandates as limiting parameters)

During the dive, the aircraft exceeded its maximum design operating envelope. While the airframe's primary fuselage held together without catastrophic mid-air breakup, post-landing inspection photos at Tabuk Airport showed that a significant portion of the aircraft's rudder had detached due to severe aerodynamic loads experienced when the plane exceeded its structural design speed limits.

IT IS A MIRACLE THAT ONLY THE RUDDER EXPERIENCED EXCESSIVE FLUTTER AND PARTIALLY DISINTEGRATED.

I dont know what the "plumber" did after watching TV show "Air Crash Investigation", but I am sure he didnt do anything because an "anari" at the controls trying to pull the yoke back to pull the aircraft from the dive which had already far exceeded the structural design limits, would have induced a whole lot of positive G (G+) which would have been catastrophic.

There is a technique to pull an aircraft out of a steep dive without further overstressing the airframe, that only a trained pilot can do in a safe manner, not by watching a TV show "Air Crash Investigation".

Whatever recovery actions were done, I am sure was done by the two "deadheading" pilots onboard. The skill of the pilots need to be appreciated on several counts, importantly

1. Display of excellent airmanship to recover the aircraft from the dive safely

2. Land the aircraft safely at Tabuk with its rudder virtually completely lost. Though I am sure the pilots would have done their "slow speed checks" after recovering from the dive and assessing the overall state of the aircraft and control response. They would surely have felt the obvious decrease in rudder response, thereby deciding on the landing plan and technique.

In aviation, deadheading refers to a commercial pilot (or flight attendant) traveling as a passenger on a commercial flight while on duty or on official company assignment.

An airline may need a crew member to fly a trip starting in another city (e.g., flying a pilot from Chicago to New York as a passenger so they can pilot a flight from New York to London).

After a crew member finishes their scheduled flight sequence or fills in for an emergency coverage gap at an outstation, the airline deadheads them back to their home base. (as was the case of the two "spare pilots" on the FlyDubai aircraft)

Deadheading (Duty Status): The pilot is on active duty, paid by the airline, and guaranteed a positive-space seat on the aircraft. They are on official company business.

Emergency Role

While deadheading pilots are off-duty in terms of operating the controls, they are still trained crew members. In rare inflight emergencies or crew incapacitation scenarios, deadheading pilots can step in to assist the working flight crew or cabin crew.