How much ice accumulation?
Just checked my log books and that flight was on January 27,1990 ( age 25 ).
Nothing is noted in my logbook about the amount of ice ( I tend to keep detailed records of things that happen during flights ) we picked up that night but I remember it was what I would consider severe icing ( aircraft wing boots would be unable to deal with it if we stayed in it too long ).
I do recall the weather was very bad in Halifax and picked up heavy ice during the approach but could not land because the DC8 freighter ( this was around 02:00 ) went off the runway due to freezing rain causing poor runway braking so we had to divert. There were no other runway options in Halifax because we needed the ILS ( was between 100 - 200 feet ceiling that night ) and that runway was closed after the DC 8 went off.
When we diverted, we eventually climbed out of the severe ice but I recall lots being on the aircraft still after we landed at our alternate , Moncton.
I honesty cannot remember how thick it was , but there was a lot stuck on the plane when we landed. The ice was affecting the performance as we had to increase power.
Anyone who says you cannot tell if you fly into severe ice doesn’t know what they are talking about , you can tell, especially if it negatively impacts the performance.
As previously mentioned, I have flown through severe ice on the Airbus ( unintentionally ) but you could not tell performance wise. Even though it was not affecting the performance, I could see ice building up on the unheated areas of the side windows and on the ice probe.
As I was saying earlier, we never used to calculate the required landing distance until about 11 years ago ( pilots ). Flight dispatch ( they still do as per regulations when generating the flight plan ) would calculate the landing distance and as long as it was enough , that was acceptable ( pilots would only know there was enough runway but not the actual amount in feet ). Problem was, this preflight calculation was based on pilots landing on that particular runway with the same weather conditions the flight dispatcher used to calculate how much runway was required but that meant there were no calculations if the pilots landed on another runway , or the weather changed meaning the calculations would be off. That said, pilots did do very basic landing distance calculations ( I mean basic ) if landing in the winter on contaminated runways covered with snow.
Things changed in the industry after a few commercial airliners ( SW B737 that went off the runway and across a highway close to a gas station ) went off the runway ( unstable approaches and touching down too far down the runway ) prompting regulatory authorizes to mandate changes to improve safety relating to approaches ( unstable ) and landings ( touch down in the touchdown zone or do a low energy go around if floating too far ).
About 11 years ago, my airline made it mandatory that we check the required landing distance prior to landing ( even though the flight dispatcher already checked it if landing on the same runway ) and brief the max distance we can float down the runway before doing a low energy go around ).
The landing calculations provide a 15% safety margin for normal landings ( oddly, regulations do not require any safety margin if landing with any type of mechanic problems ).
Lastly, because of the increased risk ( even on grooved runways according to the FAA ) of hydroplaning when moderate to heavy rain, the FAA recommend that pilots assume medium to poor braking ( input landing code 2 for medium to poor braking ) if landing in moderate to heavy rain versus just assume the runway is wet like we used to.
After the airborne landing distance calculation is completed, the pilot flying briefs the level of auto brake ( low, medium, or manual braking ) and if reverse thrust will be used ( I never use it unless the performance requires it use ).
When we put the landing gear down at about 1500 feet, we confirm ( because weather conditions may have changed on final versus what we planned for ) the level of auto braking and either leave it off, low or select medium if we feel the need for increased braking upon touchdown.
Note : our operations do not allow us to intentionally fly through severe ice or take off or land in freezing rain unless its light freezing rain.
https://www.faa.gov/about/initiatives/talpa
https://www.faa.gov/sites/faa.gov/files/about/initiatives/talpa/Airport-Operators-FAQS.pdf
