What are the rules for using OnePass miles to upgrade Northwest operated flights? Specifically:

1. Full Fares
I assume this is just Y fares. Do these book into Z?

2. Select Fares
I think B for long-haul and B, M, H, Q for North America. Do these book into I?

Depending on where you are going (Europe vs Asia) there might be a range of "Y" fares on NW, so it's best to think of Full Y, other Y and B. To Asia, there NW has YLE and YHE fares that are much. much cheaper than full Ys but upgrade at the reduced full Y mileage rate (they have a $100 change fee though). To asia, I often I see NW YLEs for only about $300 more than a NW B fare (which costs 2x miles to upgrade). I'd rather spend $300 to cut the miles in half as well as to insure easier upgrade availability. As you note, Ys upgrade to Z and Bs upgrade to I. If you peruse a fare bucket tool, you will see that I is very scarce, a few in advance and then others dumped as they realize the flight wont be full up front. All of the Y's are fairly easy to upgrade if you have +/- a day flexibility or are willing to consider slightly different routings (e.g., PDX-SIN is much more definite for upgrade than SEA-SIN).
I have more limited experiences with Europe, Y fares were pricey but fairly easy to upgrade, B fares could be really cheap, often sub $1k in the fall/winter, but ofter took tricks to get upgrades. NW uses married segments, so SEA-AMS might not have I space showing, but SEA-AMS-LHR does (even though SEA-AMS is the same plane!), so you may want to consider different destinations and using a LCC or train to patch your trip together.

To continue this thread with another question along the same lines, I'm new to CO's upgrade rules so based on what I read this morning if I book a fare in V or T and wish to upgrade, it appears as though I'll hav to shell out 40K in miles each way plus $450 each way per ticket. My wife and I are trying to book tickets to Kenya departing 1/6/07 and returning on 1/18/07 Newark, NJ to Narobi, Kenya. The fare today is $1,100 which is a great deal but adding another $900 per ticket to upgrade PLUS 80K iper ticket in miles seems a bit much to me. Yes, it's a bigger seat and better food but for the both of us to upgrade it would be $1,800 and 160K miles. Having a tough time being convinced of the value on that one.

Am I reading something wrong here? Need expert advice.

I believe there are some B fares that are considered "full fare" for upgrade purposes, but in general "full fare" means "full Y" (not just any Y).

Y fares upgrade into Z, B fares upgrade into I.

At least these are the rules for using NW miles to upgrade NW intercontinental metal. I assume the rules are similar if you're using CO miles (except you'll need to call CO to use your miles).

What economy NW select fare bases other than B are considered upgradeable using OnePass miles for North America flights?

B for sure, based upon the above posts. Also, M, H, Q and others?

For elites any regularly published intra-North-American paid fare is upgradeable with miles. For non-elites, I believe anything is upgradeable except T and K fares. At least that's what the wiki says the rules are for Worldperks members. I suspect the rules are similar (if not the same) for OnePass members.

NO surcharges apply when upgrading longhaul NWA/KLM flights on upgradeable Y/B fares using CO miles. The ticket is either upgradeable using miles, or it isn't, but in no event does CO collect extra money from the passenger as an upgrade surchage.

If you're elite with CO you can upgrade on NWA from any fare purchased

For NA routes NWA uses "R" fare bucket for upgrades

for nonelites M & B for sure...H dont believe so, Q no

I thought it was just T and K that were excluded. Or is that only for base members using WP miles and not OP miles?

Well, I believe the $450 fee only applies to upgrades into Continental's BusinessFirst. Obviously CO doesn't fly to Kenya, so I assume you are flying KLM via AMS. If you're on a CO transatlantic segment you'll definitely have to pay that fee, but I don't know how it would impact the KLM upgrade to NBO. I think you'd be better off flying KLM/NW the whole way. I don't think there's any upgrade surcharge, but I don't know if the $1100 fare will be upgradeable. You may have to purchase a more expensive fare (which may be more or less than $900 more than the lowest fare). Given that this thread can't seem to get straight the information regarding NW upgrades, I think your best bet is to call CO and hope for a competent agent who can explain this to you. Clearly, it's a bit complicated!

From nwa.com for WP mile usage (so yes you are correct...I was confusing CO Q fare)

Eligibility
Non-Elite WorldPerks members may no longer use miles to upgrade to First Class on domestic itineraries when purchasing Northwest T and K type fares or Continental V, Q, T, S and L type fares.