Reconciliation of EBITDA to Cash flow from operations

https://ir.bombardier.com/modules/misc/documents/24/13/62/83/15/Bombardier-Financial-Report-2017-en.pdf 2017 annual report link

I am trying to reconcile the EBITDA number of $611 to Net Cash Flow from Operations . $531
EBIT before special items 672
Special items 426
EBIT 246
+ Amortization 314
+ Impairment charges on PP&E and intangible assets 51
EBITDA 611
EBITDA before special items 993

First question is which EBITDA question i use? And second anyone can lay out the steps as the this company has very specific non-cash items im not familiar with?