As far as I know, Northwest was using Thales 'C16254AA' probes (the same as AF447) but as the press is not making its headlines: "NORTHWEST FAILED TO REPLACE THE PITOTS" (23 days after AF 447 crash) following AIRBUS directives bla bla bla..." like in Air France case... or maybe the new model C16254BA did freeze?... or it is another hoax.
S~
Olivier