any insights into Y overselling on KL longhaul flights? Currently AMS-LIM on Wednesday is Y3 - but business is wide open - at least 18 unoccupied seats according to the seatmap.

could Y3 indicate that Y is oversold and the flight manager will op-up some Y-passengers?

Flights in general are slightly overbooked. This is common practice with airlines.
From their homebase there will always be more no show due to missed connections.
If still oversold or to create extra revenue they all offer an Upgrade at a typical rate of 329,- E. FF members can occasionally buy an upgrade on miles in the lounge or onboard.
A free upgrade is very unlikely nowadays. Incase they offer reduced upgrades they make money and get rid of a possible overbooking in economy.
The revenue department does scan all flights for double bookings/fake bookings etc about 48 hrs before departure.

The seat map is not a good way to determine availability. Many pax have not selected seats and KL may, for one reason or another, have blocked seats.

Most carriers overbook. Oversell cannot occur until there are more passengers properly checked in and timely at the gate ready for boarding. Carriers are pretty good at overbooking enough to ensure full flights without going too far and creating an oversale.

If a cabin is oversold or at risk of oversale and there are seats in a premium cabin, KL will try to sell those seats as upgrades and then, if necessary OPUP to create space. Then and only then will it turn to denying boarding, either through volunteers, some of whom may jump at the chance not to travel, or involuntarily with EC 261/2004 compensation and rebooking.

Actual involuntary denied boarding should be rare and only occur when aircraft substitutions or broken seats throw off the calculus.

And occasionally they get it completely wrong. I recall the time LH had to leave 64 pax behind who were booked to fly JNB-FRA.

Johan

It is effectively impossible to tell from booking data if a flight will be overbooked or not. As others mention, overselling is frequent but I have been on zeroed out flights with multiple free seats, and also on flights which showed 9+ in the cheapest buckets and where cabins were overbooked.

Having taken the Lima flight recently I was surprised by the high loads on the 777-300 (100% in Eco). In my case they indeed also offered the upgrade at check in for 329 euro or so. It is a very long flight..I would advise to jump on the OLCI offer, unless you are very sure of an OPUP.

I had bid for an upgrade weeks ago but was overbid by two others. However I still won the bid for 309�.
Now in business class. All sorted out. Now the bid for upgrade for the inbound also opened. Starting bid was 329�, already two offers in the queue. The current bid needs to be 349�. According to the seatmap there are about 18 open seats in business class. Not sure whether to play poker and hope to upgrade at Checkin or place my bid now.