Dear RTO and Slasher,
Nowhere near mask drop or aircraft bending intensity. In days of yore, this particular landing would possibly not got written. The pilots rated it as just the wrong side of firm, possibly generating some 'bad FDAP numbers'.
As far as measured numbers go, we have evolved to follow Boeing's "sink rate" parameter rather than the VGTD. Capt's judgement is 'final' but still arbited by the measured numbers, so there is always a tendency to write it up in case the figures prove otherwise.
The most apt description of the situation (apologies to Slasher):
If he simply "banged it on" it means he ain't perfect just like the rest of us.
The RW and WX were fine on this occasion. The highest sink rate value was just over 8fps and LW about 4 tons under max (code D/E aircraft).
This becomes a philosophical question when it's a checkride.
Please elaborate, if you can, on the "6/10 iso 8 or 9" scale and it's usage. Our's is rather binary in outlook.
This ought to be of interest to all - to quote a Boeing study:
"Boeing reviewed 200 in-service landings to gain a greater understanding into the hard landing accuracy issues and to develop resolutions.
1. There is not a strong correlation between measured touchdown load factor
(g’s) and sink rate due to the forward location of the accelerometer.
2. Sink rate is a more accurate and reliable indication of landing severity.
. . . . .
4. The current acceleration thresholds in the AMM are considered conservative and may continue to be used without risk of missing a hard landing.
5. A large percentage of the landings above 1.9g’s appear to be firm or hard,
based on touchdown sink rate.
SINKRATE vs Vertical Speed and Vertical G:
All Boeing airplanes, including the 777 have been designed to withstand a
landing with a maximum sink rate of 10 ft/sec at the Main Gear (with the Aircraft Gross Weight at or below the Maximum Landing Weight). The ADIRU does not output a sink rate, but it does compute a Vertical Speed, based on measured air pressure. The ADIRU Vertical Speed is affected by Pitch angle, Pitch Rate, airframe flexibility, and by the 'ground effect' during landing. Specifically, the 'ground effect' during landing makes the Vertical Speed unusable for determining the sink rate during landing.
Vertical G is the most commonly used measurement to aid in the investigation of hard landings. The Vertical G is usually measured by a dedicated accelerometer in the Main Gear Wheel Well, providing a reliable measure of a hard landing.
However, on 777 the Vertical G is measured internally to the ADIRU, which is
located in the EE-bay, far forward from the Main Gear. This location subjects the Vertical G measurements to the effects of Pitch, Pitch Rate, Airframe Bending Characteristics, making it much less reliable to aid in the investigation of a hard landing. The CoG Body Normal Acceleration output by the ADIRU is based on the Vertical G and is corrected to represent the value at the Center of Gravity (for the -200 airframe). However, this correction is not perfect, and during landing the effects of Pitch, Pitch Rate, and flexibility are more significant than during steady flight. On the -300 airframe these issues are even more severe as the distance from the ADIRU to the Main Gear is greater than on the -200 airframe and the Airframe Bending Characteristics are different."
I thank you for your inputs.