I would be inclined to correct a blatant grammatical or spelling error if I'm replying to the post it's in. Why? Because if I don't, other people might think I didn't even see the error.
Most of us probably read what we've written in the preview of the post before we go ahead and post it. That is only good manners.
I make judgements about someone's education and intelligence from what they've written. What else do I have to go by? If you are informing us about something of which we were previously ignorant, I can only look at your spelling and grammar to evaluate your credibility.
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Here are the definitions pasted right out of a DOT website:
A
major airline is one that generates over $1 billion in annual operating revenues. This list currently includes Alaska Airlines, American Airlines, American Eagle, ATA Holdings, America West, Continental Air Lines, Delta Air Lines, DHL Airways, FedEx, Northwest Airlines, Southwest Airlines, United, United Parcel Service (UPS), and US Airways.
A
national airline is one that generates between $100 million and $1 billion in annual operating revenues. The national airlines tend to serve particular regions of the country; however, some do fly long-haul flights. Some examples are: AirTran, Frontier Airlines, JetBlue, and Midwest Express.
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regional airline is one that generates under $100 million in revenues and generally serves small communities. The Regional Airline Association defines regional airlines as "...operat(ing) short and medium haul scheduled airline service connecting smaller communities with larger cities and connecting hubs. The airlines' fleet primarily consists of 19 to 68 seat turboprops and 30 to 100 seat regional jets." Some examples are: American Eagle Airlines, Atlantic Southeast Airlines, Atlantic Coast Airlines, and SkyWest Airlines.