Autoflight, thank you for starting an interesting discussion.
Slasher very interesting accounts. Just for clarification in the first account you talk of an approach to MNL and the presence of moderate rain. Were there any heavy thunderstorms in the area at the time as well ? You only mention the presence of a nearby typhoon.
%MAC : The quote you give in your post showing how RGS approaches are not recommended by Boeing is for AC 00-54. Is there anywhere I can read the full article.
Mud Skipper : Just looking at some old manuals the Minimum Ground Speed approach was mentioned in the 747 Classic manuals. However it was aimed at occassions when strong winds persisted to low altitude and then disappeared before touchdown. There was also a note saying the method was not recommended for Microburst conditions, just like %MAC mentioned. Still I do agree that being aware of a minimum ground speed may be a good early warning sign that something nasty may be about to happen.
Capt. Crosswind :
"The two microburst incidents I could have been involved in I avoided by requesting a hold on both occasions.
They painted up very well on the WX radar & were clear in 15 minutes. "
I presume there was other evidence, pilot reports, ATC reports, wind differentials between wind at altitude and on the ground, presence of virga, to lead you to believe a microburst was taking place. Unless your weather radar had predictive windshear then the microburst itself cannot be painted on the radar. What you are left with then is the presence of Thunderstorms on the approach which does not necessarily mean a microburst is taking place. To quote from the National Oceanic and Atmospheric Administration website
"Observations suggest that approximately
five percent of all thunderstorms produce a microburst and significant wind damage can be related to them."
Reference :
http://www.srh.noaa.gov/jax/events/windshear.html
By the way I'm not saying that if there are thunderstorms on the approach you should carry on for approach even though there are no reports of winshear or microburst. I like you would definitely assume the worst especially if I knew from local knowledge that they would clear in a matter of minutes.
While I agree strongly with the concept of avoidance (Who could possibly disagree) one should be aware that there are aspects of microbursts that may make them impossible to avoid. We have already talked about microbursts associated with innocuous CBs. Coupled with this in a very early study of microbursts in the US it was found that they usually have a life of about 3-4 minutes. Which means it is perfectly feasible that one aircraft could fly the approach with no adverse affects whild the following aircraft could encounter a severe microburst. Again something to be aware of.