Why are Army Helo pilots Warrant Officers, rather than Commissioned?

Most Army Aviators are Warrant Officers. Even in the Fixed Wing side of the house, most of our airplane pilots are Warrants. (In the OSAA Detachments, they were originally ALL Warrant Officers, commanded by CW5's. Then someone decided to change the organization, give them an MTOE, and now I have to face a 2LT every morning when I am shaving in the mirror). The reason the Army chose to make the bulk of its Aviation personnel Warrant Officers was because they wanted an appropriate grade and courtesy bestowed upon its pilots, but did not want the O-Grade promotion/assignment process to disrupt continuity. The idea is that you have a technical officer who can devote his career to becoming an expert in his craft. Our O-Grade Officers (O-Grade is a term we use since CW2's and above are "legally" commissioned officers) are still pilots, but unfortunately that role is often times secondary to their chosen path to be managers of the organization. At least we have a Branch now. There was a time that other branch officers (Infantry, Engineer, Artillery,etc) would be "Branch Detailed" to Aviation to serve as the leadership. The problem was you had an Infantry Officer who just wounded his competitiveness with other Infantry Officers by spending valuable years of his career doing "non-Infantry" things. The creation of the Aviation Branch was intended to correct that issue.

An Army Warrant Officer will spend most of their career in operational flying positions, whereas our O-grades will do their platoon and company time and spend the rest of their careers in Staff positions. A few will become Battalion and Brigade Commanders. A microscopic few will ever see General Officer, but most of our hemorrhage on the O-Grade side of the house comes around the O-3 level. Many Army Captains will have fulfilled their mandatory service obligation after 6 years, see the proverbial flying desk ahead, and will separate, branch transfer, or some will revert to Warrant Officer (happens a lot more in the Guard and Reserves than in the Active Component.) Those that stay to see the oak leaf aren't spending too much time in a cockpit.

Having seen both sides of the coin, I see the intent. The idea was to create a system where guys aren't promoted out of a cockpit too fast. For the most part, it works, but as a Warrant Officer sees CW3 and above, he starts seeing the Staff Monster creeping around the corner more and more. At least he still gets to fly once in a while.

Having served as an Army Warrant Officer pilot and as a commissioned officer pilot in the Coast Guard, I can tell you that a lot of the reasoning has to do with sheer numbers and cost. Congress mandates how many commissioned officers each service can have. It doesn't mandate how many warrant officers it can have so the Army takes advantage of that. The Army has more aircraft than the Air Force and a lot more pilots. So having them as warrant officers helps a few things.

It allows them to have more pilots at an overall lower cost than if all the pilots were commissioned and they don't have to have a bunch of officers competing for a very limited amount of leadership positions.

In other services, the commissioned officer pilots are always looking for additional jobs to do outside of aviation so they have something to show when it becomes time to get promoted or get looked at for command. A warrant officer pilot does his best to avoid additional jobs or even get looked at by the command. That way they can focus on doing the job of flying and figuring out how to leave early and avoid PT.

In other services, the youngest pilot in the unit will be about 23 years old, college educated, ponders decisions, and looks down on those who are not as gentlemanly as they are. A warrant officer pilot could be as young as 19, with no college education, tends not to over think things, says "watch this" a lot, and gives a big F U to those who think they are better than they are.

In other services, the pilots eat their own. It is a struggle to get the support you need from your fellow officers especially those at the same rank because they see you as competition. Warrant Officer pilots create a pack. Often known as the WOLF pack or Warrant Officer Liberation Front. If you mess with one, you mess with the who pack and have been known to make or break commissioned officer's careers. But be warned, if you are a warrant officer that is not deemed worthy, you will be fed to the commissioned officers as an offering.

In other services, the pilots have to stay in nice lodging wherever they go and scorn anything less than a four star hotel. In the Army, the warrant officer pilots get a GP medium and brag they don't have to sleep on the ground. If given the opportunity to stay in something with four solid walls and a roof, they constantly worry about when someone will come in and tell them there was a mistake and be told to move. Because of that, they never unpack their bags.

My understanding is it was originally the Army's way of working around the congressional restrictions on the number of officers between the O-1 and O-4 as well as the advantage of having a Warrant specializing in flight duties without being distracted by other duties associated with the O ranks. Warrants were also paid less base and flight pay until the 70s. They also had a faster and more responsive fill rate than the O officers.
I don't know the current status, but during VN their was also a difference in the training level, with the Warrants not getting some of the advanced training provided to other pilots and aviators (instruments)
All that aside, Warrant Officer pilots have proven their skill, bravery and dedication since they were established after WWII