When major airlines place orders, they tend to be on a large scale. And with two major airlines having made their order decisions in the past week, it's time to see how these developments will affect the world's top aerospace manufacturers.

Canadian order
In a previous article, I discussed the approaching order that Air Canada (TSX:AC.B) would be expected to make for a renewal of its narrowbody fleet. In the end, Boeing (NYSE:BA) won the contest, as Air Canada placed an order for 33 Boeing 737MAX 8 aircraft, and 28 larger Boeing 737MAX 9 aircraft for a total order of 61 jets valued at more than $6 billion.

Bloomberg notes this selection as particularly significant for Boeing, because it has allowed the manufacturer to break into Air Canada's narrowbody fleet, a fleet previously dominated by Airbus, a subsidiary of European Aeronautic Defense and Space Company. Air Canada already operates many Boeing models in its widebody fleet, and is aggressively promoting the introduction of the Boeing 787 Dreamliner, scheduled to begin in early 2014.

American order
In building the world's largest airline, American Airlines Group (NASDAQ:AAL) has been very aggressive when it comes to fleet modernization. In mid 2011, the airline placed a $40 billion order for 460 jets in a massive order split between Boeing and Airbus. In November of that year, American declared bankruptcy, but the order was allowed to continue as part of the way to make a reorganized American Airlines more viable.

The latest order decision has been months in waiting, but American has finally placed an order for renewal of its regional jet fleet. As top regional jet rivals, Embraer SA (NYSE:ERJ) and Bombardier (TSX:BBD.B) have been the lead contenders for this order. The final results had American order 60 Embraer E175 jets and 30 Bombardier CRJ900 NextGen jets in an order valued around $4 billion.

Of note is that both this order, and the Air Canada order, include options to purchase additional aircraft, a fairly common addition to aircraft orders. Because of this option granting, aerospace manufacturers are in an excellent position to benefit from increasing fortunes at Air Canada and American Airlines Group.

Future orders
Looking toward the future, Boeing may have greater opportunities in Air Canada's narrowbody fleet if the airline does another round of fleet modernization. However, the next priority for Air Canada will be the decision for a regional jet order setting up tough competition in this sub-industry.

There are already reports of talks between Air Canada and Bombardier regarding a potential purchase of Bombardier's new C Series aircraft. Purchasing these planes would make a great homegrown manufacturing story for Air Canada at the same time as many analysts are questioning Bombardier's ability to meet its target of 300 C Series orders by launch.

American's decision to split its 2011 order between Boeing and Airbus, and its most recent order between Embraer and Bombardier, signifies that American is willing to have a fleet diverse in manufacturers. Therefore, future orders from American also carry a great possibility of being split between multiple manufacturers. Aerospace manufacturing investors should keep this in mind next time there are reports that American is getting ready to place an order.

Securing your future

Alexander MacLennan owns shares of Air Canada. He is also long $17 January 2015 calls on American Airlines Group. This article is not an endorsement to buy or sell any security and does not constitute professional investment advice. Always do your own due diligence before buying or selling any security. The Motley Fool recommends Embraer-Empresa Brasileira. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.